Tyrimo tikslas buvo įvertinti sensitizaciją ŽLA antigenais, inksto transplantatų recipientams, kurie greta standartinės imunosupresijos vartojo monokloninius antikūnus prieš IL-2 receptorių ir monokloninių antikūnų nevartojusiems recipientams. Tyrime dalyvauja VULSK pacientai, kuriems 2000-2005 metais imtinai buvo atliktos inkstų transplantacijos (Tx), bei kurie prieš ir po Tx buvo tirti dėl teigiamai su limfocitų panele reaguojančių antikūnų skaičiaus, išreikšto procentais (PRA). Iš viso tyrime dalyvauja 189 recipientai. Dalis jų (n=83) greta standartinės imunosupresijos vartojo monokloninius antikūnus prieš IL-2 receptorių (basiliksimabą ar daklizumabą), kiti (n=106) gavo tik standartinę imunosupresiją. Pagrindiniai sensitizaciją ŽLA antigenais lemiantys veiksniai abiejose grupėse pasiskirstė nevienodai. Didesnė monokloninius antikūnus vartojusių dalis gavo kraujo perpylimus (72% vs. 57,3%), šioje grupėje taip pat daugiau buvo pakartotinų Tx (9,6% vs. 7,5%), tik gimdžiusių moterų skaičius didesnis buvo monokloninių antikūnų nevartojusioje grupėje (47,7% vs. 30,8%). Tirtos ligonių grupės palygintos taikant &#967;² kriterijų, skirtumas laikytas statistiškai reikšmingas, kai p<0,05. Išanalizavus recipientų sensitizaciją prieš Tx paaiškėjo, kad dauguma (58%; 110/189) buvo nesensitizuoti (PRA 0-10%), likę 42% (79/189) - sensitizuoti, iš kurių 14% (11/189) – labai sensitizuoti (PRA 50-100%). Po Tx monokloninius antikūnus vartojusių recipientų grupėje (n=83) 2% padaugėjo... [toliau žr. visą tekstą] / The aim of this study was to evaluate the sensitization with HLA antigens in kidney transplant recipients, who received induction therapy with monoclonal antibodies against IL-2R and in the group of patients, who were only under the triple drug therapy. This study comprises recipients, who received kidney transplant in the year 2000-2005, and who were tested for panel reactive antibody test before and after transplantation (Tx). The total number of 189 kidney transplant recipients takes part in this study. 83 received monoclonal antibodies against IL-2R (basiliximab or daclizumab), others (n=106) – did not. These groups were unequal in comparison to the main factors causing sensitization with HLA antigens. The group of patients, who received induction therapy with monoclonal antibodies had more blood transfuzions (72% vs. 57,3%), and previous transplantations (9,6% vs. 7,5%), in comparison with the other group. Only the number of pregnancies was higher in the group of patients who were only under the triple drug therapy (47,7% vs. 30,8%). Statistical analyses were caried out using chi-square test, differences were considered significant at p<0,05. 58% (110/189) of kidney transplant recipients were unsensitized (PRA 0-10%) before Tx, the rest 42% (79/189) were sensitized, from which 14% (11/189) were highly sensitized (PRA 50-100%). After Tx the number of medium sensitized (PRA 11-50%) kidney transplant recipients, who received induction therapy by monoclonal antibodies... [to full text]

Introdução: Testes de histocompatibilidade são indispensáveis para viabilizar o transplante renal. A prova cruzada por citotoxicidade dependente de complemento (CDC) tem sido a técnica padrão para avaliar risco imunológico pré-transplante, no entanto, a prova cruzada por citometria de fluxo (FCXM) possui benefícios adicionais, como maior sensibilidade e análise semi-quantitativa através do Median Channel Shift (MCS). Objetivo: Definir pontos de corte de MCS baseado em correlação inter-técnicas e desfechos clínicos pós-transplante. Método: Estudo retrospectivo com pacientes candidatos a transplante renal no Hospital de Clínicas de Porto Alegre, entre janeiro/2016-agosto/2017. Foram avaliadas 1705 provas cruzadas e 221 pacientes submetidos ao transplante. Resultados: A FCXM, relacionada ao CDC, apresentou sensibilidade=87%(FCXM-T) e 90%(FCXM-B), e VPN=98% para ambos. FCXM-B apresentou especificidade=43%, relacionada aos casos CDC-/FCXMB+. FCXM-T e -B detectaram 53% e 76% dos casos de DSA≥5001 (Donor Specific Antibody). MCS apresentou desempenho satisfatório em detectar CDC+ (AUC/IC): MCST=0,909(0,886-0,933) e MCSB=0,775(0,724-0,826). Pontos de corte de MCST=245 e MCSB=282 apresentaram melhor predição de CDC+. Não houve diferença na função do enxerto de pacientes transplantados com FCXM+. Apenas 30% das FCXM+ estiveram diretamente relacionadas com DSA pré-tx. No entanto, episódios de rejeição foram mais frequentes no grupo FCXM+vs.FCXM- (95%vs.86%, p=0,04). Conclusão: É possível calibrar o MCS baseado no CDC+, no entanto, significa um risco em termos da não detecção de anticorpos de baixo título. A FCXM+, em curto prazo, não deve ser por si só um fator impeditivo para o transplante. A análise conjunta do MCS e DSA parece ser uma boa ferramenta de seleção dos receptores renais. / Introduction: Histocompatibility tests are indispensable for enable the renal transplantation. Crossmatching tests for complement dependent cytotoxicity (CDC) has been a standard technique for assess pre-transplant immunological risk, however, the flow cytometry crossmatching test (FCXM) has additional benefits, such as increased sensitivity and semi-quantitative analysis through the Median Channel Shift (MCS). Objective: Define MCS cutoff values based on inter-technical correlation and post-transplant clinical outcomes. Methods: A retrospective study with renal transplant candidates at the Hospital de Clínicas of Porto Alegre, between January/2016-August/2017. A total of 1705 crossmatching and 221 patients submitted to transplantation were evaluated. Results: The FCXM, related to CDC, resulted in sensitivity=87% (FCXM-T) and 90% (FCXM-B), and NPV=98%, for both. FCXM-B resulted in specificity=43%, related to cases CDC-/FCXMB+. FCXM-T and -B detected 53% and 76% of cases of DSA≥5001 (Donor Specific Antibody). The MCS showed satisfactory performance in detecting CDC + (AUC/IC): MCST=0.909(0.886-0.933) and MCSB=0.775(0.724-0.826). Cutoff values of MCST=245 and MCSB=282 showed better prediction of CDC+. There was no difference in the graft function of patients transplanted with FCXM+. Only 30% of FCXM + were directly related to pre-tx DSA. However, rejection episodes were more frequent in the group FCXM+vs.FCXM- (95%vs.86%, p=0,04). Conclusion: it is possible to calibrate MCS based on CDC +, however, that means a risk in terms as to the non-detection of low-titre antibodies. The FCXM+, in the short term, should not be by itself an impediment to transplantation. Joint analysis of MCS and DSA seems to be a good tool for selection of renal receptors.

Introdução: A relevância clínica da presença de anticorpos anti-HLA após o transplante renal tem sido foco de recente atenção para os estudiosos da histocompatibilidade. Pacientes que possuem anticorpos anti-HLA no póstransplante apresentam maior incidência de rejeição aguda (RA) e de nefropatia crônica do enxerto (NCE). Como conseqüência, alguns perdem o órgão transplantado ou sofrem com as reações imunopatológicas correspondentes. Entretanto, existem algumas controvérsias sobre o grau de valorização da presença desses anticorpos na etiopatogenia da RA e da NCE, pois nem todos os pacientes com anticorpos evoluem mal. Objetivo: Avaliar a presença de anticorpos anti-HLA no primeiro ano do transplante renal e verificar sua associação com a ocorrência de RA e NCE. Pacientes e Método: Este estudo incluiu consecutivamente 88 pacientes submetidos a transplante renal no Serviço de Nefrologia do Hospital de Clínicas de Porto Alegre, entre outubro de 2002 a outubro de 2004. Amostras de sangue foram colhidas no 1º, 3º, 6º e 12º meses pós-transplante renal, visando à pesquisa de anticorpos IgG anti-HLA de classes I e II. Nos pacientes que consentiram, biópsias renais de protocolo foram realizadas entre o 2º e o 3º mês e no 12º mês póstransplante. A detecção dos anticorpos foi realizada através de ensaio ELISA (LATM e LAT-1240, One Lambda Inc., USA). Rejeição aguda e a NCE foram diagnosticadas por critérios clínicos, laboratoriais e histopatológicos. Resultados: Oitenta e oito pacientes foram avaliados, sendo 40 (45,5%) do sexo feminino e setenta e dois (81,8%) de etnia caucasóide. Setenta e um (80,6%) receberam rins de doador falecido. Foi detectada a presença de anticorpos anti-HLA em vinte pacientes (22,7%). Desses, somente 3 (4,4%) desenvolveram anticorpos anti-HLA (classe I) no período pós-transplante; os demais (17) já os apresentavam no período prétransplante. No seguimento até um ano, 23 pacientes (26,1%) apresentaram RA e 43 (51,2%) desenvolveram NCE. Nove (45%) pacientes com anticorpos no póstransplante desenvolveram RA contra 14 (20,6%) dos sem anticorpos (P=0,058). Entre os pacientes com anticorpos no pós-transplante, 11 (64,7%) desenvolveram NCE contra 32 (47,8%) dos sem anticorpos (P=0,329). Na análise histológica, os anticorpos anti-HLA foram associados à RA IIA (P=0,001) e à NCE grau II (P= 0,012). As variáveis preditoras para a RA e NCE foram, respectivamente, presença de anticorpos anti-HLA de classe I no 1º mês pós-transplante (OR= 4,30; IC 95%= 1,32-14,1; P= 0,016) e transplante com órgão de doador-limítrofe (OR= 4,81; IC 95%= 1,18-20,3; P= 0,028). Setenta por cento (70%) dos pacientes com RA desenvolveram NCE, contra 45,3% dos pacientes sem RA (P= 0,054). Conclusão: Os anticorpos anti-HLA presentes no primeiro ano do transplante renal foram associados a RA e NCE. A pesquisa de anticorpos anti-HLA no pós-transplante renal realizada por outros pesquisadores e aqui também avaliada, se adotada como rotina, possibilitaria a identificação de casos de mau prognóstico e a escolha de planos terapêuticos mais adequados. A correlação entre anticorpos anti-HLA e rejeição deverá se tornar mais evidente com o passar dos anos, sendo que nossos resultados fortalecem a convicção da necessidade de continuidade desses estudos. / Introduction: The clinical relevance of the presence of anti-HLA antibodies following kidney transplant has been the recent focus of attention of histocompatibility researchers. Patients who present anti-HLA antibodies in the post-transplant period have shown higher incidence of acute rejection (AR) and of chronic allograft nephropathy (CAN). As a result, some lose the transplanted organ or suffer from the corresponding immunopathological reactions. However, there has been some controversy as to the importance of the presence of these antibodies in the ethiopathology of AR and CAN, since not all patients who have these antibodies present the same outcome. Objective: To evaluate the presence of anti-HLA antibodies during the first year of kidney transplantation and to check its association with the occurrence of AR and CAN. Patients and Method: This research included consecutively 88 patients who had undergone kidney transplants in the Hospital de Clínicas de Porto Alegre Nephrology Service between October 2002 and October 2004. Blood samples were taken during the 1st, 3rd, 6th and 12th months post kidney transplant, aiming at researching for Class I and II IgG anti-HLA antibodies. In consenting patients, protocol kidney biopsies were carried out between the 2nd and 3rd months and in the 12th month after the transplant. Detection of antibodies was done through ELISA test (LAT-M and LAT-1240, One Lambda Inc., USA). Acute rejection and CAN were diagnosed through clinical, laboratorial and histopathological criteria. Results: Eighty-eight patients were evaluated, among which 40 (45.5%) were female and seventy-two (81.8%) were Caucasian. Seventy-one (80.6%) received kidneys from deceased donors. The presence of anti-HLA antibodies was found in 20 patients (22.7%). Among these, only 3 (4.4%) developed anti-HLA antibodies (class I) during the post-transplant period; the remaining (17) already presented these antibodies during the pre-transplant period. In the follow-up up to one year, 23 patients (26.1%) presented AR and 43 (51.2%) developed CAN. Nine patients (45%) with antibodies in the post-transplant period developed AR as opposed to 14 (20.6%) patients without antibodies (P=0.058). Among the patients with antibodies in the post-transplant period, 11 (64.7%) developed CAN as opposed to 32 (47.8%) of those without antibodies (P=0.329). In the histological analysis, the anti-HLA antibodies were associated to AR IIA (P=0.001) and to CAN degree II (P= 0.012). The predictive variables for AR and CAN were, respectively, the presence of Class I anti-HLA antibodies in the first month post-transplant (OR= 4.30; IC 95%= 1.32-14.1; P= 0.016) and transplant with expanded criteria donors (OR= 4.81; IC 95%= 1.18-20.3; P= 0.028). Seventy per cent of the patients presenting AR developed CAN, as opposed to 45.3% of the patients without AR (P= 0.054). Conclusion: The anti-HLA antibodies present in the first year of the kidney transplant were associated to AR and CAN. The research of anti-HLA antibodies in the kidney post-transplant period carried by other researchers, as well as in this study, if done routinely, would allow the identification of cases with a poor prognosis and the choice of more adequate treatments. The correlation of anti-HLA antibodies and rejection will become more evident with time, and our results reinforce the certainty that these studies must continue.

Introdução: A relevância clínica da presença de anticorpos anti-HLA após o transplante renal tem sido foco de recente atenção para os estudiosos da histocompatibilidade. Pacientes que possuem anticorpos anti-HLA no póstransplante apresentam maior incidência de rejeição aguda (RA) e de nefropatia crônica do enxerto (NCE). Como conseqüência, alguns perdem o órgão transplantado ou sofrem com as reações imunopatológicas correspondentes. Entretanto, existem algumas controvérsias sobre o grau de valorização da presença desses anticorpos na etiopatogenia da RA e da NCE, pois nem todos os pacientes com anticorpos evoluem mal. Objetivo: Avaliar a presença de anticorpos anti-HLA no primeiro ano do transplante renal e verificar sua associação com a ocorrência de RA e NCE. Pacientes e Método: Este estudo incluiu consecutivamente 88 pacientes submetidos a transplante renal no Serviço de Nefrologia do Hospital de Clínicas de Porto Alegre, entre outubro de 2002 a outubro de 2004. Amostras de sangue foram colhidas no 1º, 3º, 6º e 12º meses pós-transplante renal, visando à pesquisa de anticorpos IgG anti-HLA de classes I e II. Nos pacientes que consentiram, biópsias renais de protocolo foram realizadas entre o 2º e o 3º mês e no 12º mês póstransplante. A detecção dos anticorpos foi realizada através de ensaio ELISA (LATM e LAT-1240, One Lambda Inc., USA). Rejeição aguda e a NCE foram diagnosticadas por critérios clínicos, laboratoriais e histopatológicos. Resultados: Oitenta e oito pacientes foram avaliados, sendo 40 (45,5%) do sexo feminino e setenta e dois (81,8%) de etnia caucasóide. Setenta e um (80,6%) receberam rins de doador falecido. Foi detectada a presença de anticorpos anti-HLA em vinte pacientes (22,7%). Desses, somente 3 (4,4%) desenvolveram anticorpos anti-HLA (classe I) no período pós-transplante; os demais (17) já os apresentavam no período prétransplante. No seguimento até um ano, 23 pacientes (26,1%) apresentaram RA e 43 (51,2%) desenvolveram NCE. Nove (45%) pacientes com anticorpos no póstransplante desenvolveram RA contra 14 (20,6%) dos sem anticorpos (P=0,058). Entre os pacientes com anticorpos no pós-transplante, 11 (64,7%) desenvolveram NCE contra 32 (47,8%) dos sem anticorpos (P=0,329). Na análise histológica, os anticorpos anti-HLA foram associados à RA IIA (P=0,001) e à NCE grau II (P= 0,012). As variáveis preditoras para a RA e NCE foram, respectivamente, presença de anticorpos anti-HLA de classe I no 1º mês pós-transplante (OR= 4,30; IC 95%= 1,32-14,1; P= 0,016) e transplante com órgão de doador-limítrofe (OR= 4,81; IC 95%= 1,18-20,3; P= 0,028). Setenta por cento (70%) dos pacientes com RA desenvolveram NCE, contra 45,3% dos pacientes sem RA (P= 0,054). Conclusão: Os anticorpos anti-HLA presentes no primeiro ano do transplante renal foram associados a RA e NCE. A pesquisa de anticorpos anti-HLA no pós-transplante renal realizada por outros pesquisadores e aqui também avaliada, se adotada como rotina, possibilitaria a identificação de casos de mau prognóstico e a escolha de planos terapêuticos mais adequados. A correlação entre anticorpos anti-HLA e rejeição deverá se tornar mais evidente com o passar dos anos, sendo que nossos resultados fortalecem a convicção da necessidade de continuidade desses estudos. / Introduction: The clinical relevance of the presence of anti-HLA antibodies following kidney transplant has been the recent focus of attention of histocompatibility researchers. Patients who present anti-HLA antibodies in the post-transplant period have shown higher incidence of acute rejection (AR) and of chronic allograft nephropathy (CAN). As a result, some lose the transplanted organ or suffer from the corresponding immunopathological reactions. However, there has been some controversy as to the importance of the presence of these antibodies in the ethiopathology of AR and CAN, since not all patients who have these antibodies present the same outcome. Objective: To evaluate the presence of anti-HLA antibodies during the first year of kidney transplantation and to check its association with the occurrence of AR and CAN. Patients and Method: This research included consecutively 88 patients who had undergone kidney transplants in the Hospital de Clínicas de Porto Alegre Nephrology Service between October 2002 and October 2004. Blood samples were taken during the 1st, 3rd, 6th and 12th months post kidney transplant, aiming at researching for Class I and II IgG anti-HLA antibodies. In consenting patients, protocol kidney biopsies were carried out between the 2nd and 3rd months and in the 12th month after the transplant. Detection of antibodies was done through ELISA test (LAT-M and LAT-1240, One Lambda Inc., USA). Acute rejection and CAN were diagnosed through clinical, laboratorial and histopathological criteria. Results: Eighty-eight patients were evaluated, among which 40 (45.5%) were female and seventy-two (81.8%) were Caucasian. Seventy-one (80.6%) received kidneys from deceased donors. The presence of anti-HLA antibodies was found in 20 patients (22.7%). Among these, only 3 (4.4%) developed anti-HLA antibodies (class I) during the post-transplant period; the remaining (17) already presented these antibodies during the pre-transplant period. In the follow-up up to one year, 23 patients (26.1%) presented AR and 43 (51.2%) developed CAN. Nine patients (45%) with antibodies in the post-transplant period developed AR as opposed to 14 (20.6%) patients without antibodies (P=0.058). Among the patients with antibodies in the post-transplant period, 11 (64.7%) developed CAN as opposed to 32 (47.8%) of those without antibodies (P=0.329). In the histological analysis, the anti-HLA antibodies were associated to AR IIA (P=0.001) and to CAN degree II (P= 0.012). The predictive variables for AR and CAN were, respectively, the presence of Class I anti-HLA antibodies in the first month post-transplant (OR= 4.30; IC 95%= 1.32-14.1; P= 0.016) and transplant with expanded criteria donors (OR= 4.81; IC 95%= 1.18-20.3; P= 0.028). Seventy per cent of the patients presenting AR developed CAN, as opposed to 45.3% of the patients without AR (P= 0.054). Conclusion: The anti-HLA antibodies present in the first year of the kidney transplant were associated to AR and CAN. The research of anti-HLA antibodies in the kidney post-transplant period carried by other researchers, as well as in this study, if done routinely, would allow the identification of cases with a poor prognosis and the choice of more adequate treatments. The correlation of anti-HLA antibodies and rejection will become more evident with time, and our results reinforce the certainty that these studies must continue.

Introdução: A relevância clínica da presença de anticorpos anti-HLA após o transplante renal tem sido foco de recente atenção para os estudiosos da histocompatibilidade. Pacientes que possuem anticorpos anti-HLA no póstransplante apresentam maior incidência de rejeição aguda (RA) e de nefropatia crônica do enxerto (NCE). Como conseqüência, alguns perdem o órgão transplantado ou sofrem com as reações imunopatológicas correspondentes. Entretanto, existem algumas controvérsias sobre o grau de valorização da presença desses anticorpos na etiopatogenia da RA e da NCE, pois nem todos os pacientes com anticorpos evoluem mal. Objetivo: Avaliar a presença de anticorpos anti-HLA no primeiro ano do transplante renal e verificar sua associação com a ocorrência de RA e NCE. Pacientes e Método: Este estudo incluiu consecutivamente 88 pacientes submetidos a transplante renal no Serviço de Nefrologia do Hospital de Clínicas de Porto Alegre, entre outubro de 2002 a outubro de 2004. Amostras de sangue foram colhidas no 1º, 3º, 6º e 12º meses pós-transplante renal, visando à pesquisa de anticorpos IgG anti-HLA de classes I e II. Nos pacientes que consentiram, biópsias renais de protocolo foram realizadas entre o 2º e o 3º mês e no 12º mês póstransplante. A detecção dos anticorpos foi realizada através de ensaio ELISA (LATM e LAT-1240, One Lambda Inc., USA). Rejeição aguda e a NCE foram diagnosticadas por critérios clínicos, laboratoriais e histopatológicos. Resultados: Oitenta e oito pacientes foram avaliados, sendo 40 (45,5%) do sexo feminino e setenta e dois (81,8%) de etnia caucasóide. Setenta e um (80,6%) receberam rins de doador falecido. Foi detectada a presença de anticorpos anti-HLA em vinte pacientes (22,7%). Desses, somente 3 (4,4%) desenvolveram anticorpos anti-HLA (classe I) no período pós-transplante; os demais (17) já os apresentavam no período prétransplante. No seguimento até um ano, 23 pacientes (26,1%) apresentaram RA e 43 (51,2%) desenvolveram NCE. Nove (45%) pacientes com anticorpos no póstransplante desenvolveram RA contra 14 (20,6%) dos sem anticorpos (P=0,058). Entre os pacientes com anticorpos no pós-transplante, 11 (64,7%) desenvolveram NCE contra 32 (47,8%) dos sem anticorpos (P=0,329). Na análise histológica, os anticorpos anti-HLA foram associados à RA IIA (P=0,001) e à NCE grau II (P= 0,012). As variáveis preditoras para a RA e NCE foram, respectivamente, presença de anticorpos anti-HLA de classe I no 1º mês pós-transplante (OR= 4,30; IC 95%= 1,32-14,1; P= 0,016) e transplante com órgão de doador-limítrofe (OR= 4,81; IC 95%= 1,18-20,3; P= 0,028). Setenta por cento (70%) dos pacientes com RA desenvolveram NCE, contra 45,3% dos pacientes sem RA (P= 0,054). Conclusão: Os anticorpos anti-HLA presentes no primeiro ano do transplante renal foram associados a RA e NCE. A pesquisa de anticorpos anti-HLA no pós-transplante renal realizada por outros pesquisadores e aqui também avaliada, se adotada como rotina, possibilitaria a identificação de casos de mau prognóstico e a escolha de planos terapêuticos mais adequados. A correlação entre anticorpos anti-HLA e rejeição deverá se tornar mais evidente com o passar dos anos, sendo que nossos resultados fortalecem a convicção da necessidade de continuidade desses estudos. / Introduction: The clinical relevance of the presence of anti-HLA antibodies following kidney transplant has been the recent focus of attention of histocompatibility researchers. Patients who present anti-HLA antibodies in the post-transplant period have shown higher incidence of acute rejection (AR) and of chronic allograft nephropathy (CAN). As a result, some lose the transplanted organ or suffer from the corresponding immunopathological reactions. However, there has been some controversy as to the importance of the presence of these antibodies in the ethiopathology of AR and CAN, since not all patients who have these antibodies present the same outcome. Objective: To evaluate the presence of anti-HLA antibodies during the first year of kidney transplantation and to check its association with the occurrence of AR and CAN. Patients and Method: This research included consecutively 88 patients who had undergone kidney transplants in the Hospital de Clínicas de Porto Alegre Nephrology Service between October 2002 and October 2004. Blood samples were taken during the 1st, 3rd, 6th and 12th months post kidney transplant, aiming at researching for Class I and II IgG anti-HLA antibodies. In consenting patients, protocol kidney biopsies were carried out between the 2nd and 3rd months and in the 12th month after the transplant. Detection of antibodies was done through ELISA test (LAT-M and LAT-1240, One Lambda Inc., USA). Acute rejection and CAN were diagnosed through clinical, laboratorial and histopathological criteria. Results: Eighty-eight patients were evaluated, among which 40 (45.5%) were female and seventy-two (81.8%) were Caucasian. Seventy-one (80.6%) received kidneys from deceased donors. The presence of anti-HLA antibodies was found in 20 patients (22.7%). Among these, only 3 (4.4%) developed anti-HLA antibodies (class I) during the post-transplant period; the remaining (17) already presented these antibodies during the pre-transplant period. In the follow-up up to one year, 23 patients (26.1%) presented AR and 43 (51.2%) developed CAN. Nine patients (45%) with antibodies in the post-transplant period developed AR as opposed to 14 (20.6%) patients without antibodies (P=0.058). Among the patients with antibodies in the post-transplant period, 11 (64.7%) developed CAN as opposed to 32 (47.8%) of those without antibodies (P=0.329). In the histological analysis, the anti-HLA antibodies were associated to AR IIA (P=0.001) and to CAN degree II (P= 0.012). The predictive variables for AR and CAN were, respectively, the presence of Class I anti-HLA antibodies in the first month post-transplant (OR= 4.30; IC 95%= 1.32-14.1; P= 0.016) and transplant with expanded criteria donors (OR= 4.81; IC 95%= 1.18-20.3; P= 0.028). Seventy per cent of the patients presenting AR developed CAN, as opposed to 45.3% of the patients without AR (P= 0.054). Conclusion: The anti-HLA antibodies present in the first year of the kidney transplant were associated to AR and CAN. The research of anti-HLA antibodies in the kidney post-transplant period carried by other researchers, as well as in this study, if done routinely, would allow the identification of cases with a poor prognosis and the choice of more adequate treatments. The correlation of anti-HLA antibodies and rejection will become more evident with time, and our results reinforce the certainty that these studies must continue.

Le TRALI représente un œdème pulmonaire lésionnel aigu survenant au cours d’une transfusion. Son mécanisme étiopathologique encore très imprécis conduit aujourd’hui à une sous-estimation de son incidence. Des études clinico-anatomiques ont souligné le rôle central des polynucléaires neutrophiles (PMN) en montrant que le TRALI résulte de l’accumulation de PMN au contact de l’endothélium lésé des capillaires pulmonaires. De nombreux investigateurs ont tenté de définir le facteur déclenchant présent dans le produit sanguin transfusé et évoquèrent l’existence d’un conflit immunologique par infusion d’anticorps anti-HLA. En appui avec les données de la littérature, ce travail a pour but d’apporter une meilleure connaissance du mécanisme du TRALI afin d’en améliorer son diagnostic, sa prévention et la prise en charge du patient. Tout d’abord, nous confirmons l’implication des anticorps anti-HLA dans la survenue du TRALI en validant pour la première fois l’hypothèse du modèle en deux étapes: une première étape préalable est requise chez le patient présentant une situation clinique ou thérapeutique prédisposante qui aboutit à une pré-stimulation des PMN, puis une seconde étape, dépendante de l’apport d’anticorps anti-HLA lors de la transfusion, entraîne l’activation de la NADPH oxydase phagocytaire. Cela conduit à l’activation des PMN et la libération de dérivés réactifs de l’oxygène qui sont directement responsables de la lésion endothéliale pulmonaire et provoque une augmentation de la perméabilité endothéliale. Nous démontrons en plus l’existence d’un seuil d’anticorps anti-HLA nécessaire pour déclencher une forte activation des PMN. Enfin, nous avons mis en évidence un mécanisme d’activation des PMN par les anticorps anti-HLA faisant intervenir la formation de complexes immuns antigène – anticorps à la surface des PMN. Ces complexes immuns sont reconnus avec une affinité plus grande que les anticorps seuls par les récepteurs Fc des PMN. Cette double interaction au sein d’un même PMN pourrait favoriser la formation de cluster de récepteurs Fc activés au niveau de radeaux lipidiques, ce qui induirait une activation optimisée de ces récepteurs, entraînant une cascade de signalisation aboutissant à l’activation de la NADPH oxydase des PMN. Nos résultats constituent un rationnel scientifique solide pour accéder à une meilleure connaissance du TRALI. / TRALI represents an acute non-cardiogenic pulmonary oedema following blood transfusion. The unknown etiopathological mechanism of TRALI leads to an underestimation of the incidence. Clinical and anatomical studies highlighted the major role of neutrophils (PMN) and showed that TRALI results from an increased number of neutrophils within the pulmonary capillary endothelium. Many evidence suggest that antibodies recognizing human leukocyte antigens (HLA) present in the blood transfusion are the predominant trigger leading to TRALI. Towards theses findings, we investigated the precise mechanism in TRALI in order to get a better knowledge of its diagnosis, its prevention and the patient care. We confirm the major role of anti-HLA antibodies and validate for the first time the two-hit model: the first-hit related to the patient clinical condition leads to their PMN stimulation, followed in the second-hit by the infusion of blood products containing anti-HLA antibodies that activate the phagocytic NADPH oxidase. This event induces PMN activation and the release of reactive oxygen species that are directly responsible for the pulmonary endothelial damage and cause the endothelial permeability increase. We also demonstrate the cut-off of anti-HLA antibodies that raises PMN activation. Finally, we showed that both the antigen-binding and the Fc-binding systems to antibodies are needed to induce a major PMN activation. We found that the binding of anti-HLA antibodies to HLA antigens promote the formation of cluster of Fc receptors within lipid rafts. The translocation of Fc receptors into lipid rafts improve Fc receptors activation, leading to intracellular signal transduction and activation of effector functions, such as NADPH oxidase activation and release of reactive oxygen species involved in tissue damage.

Contexte : La réponse allo-immune induite par la transplantation à partir d'un donneur génétiquement différent est un obstacle majeur au succès de la greffe. Notre objectif est de caractériser les différents phénotypes de rejet d'allogreffe rénale et d'identifier la façon dont chacun est associé aux anticorps anti-HLA. Nous avons également évalué l’impact de certaines propriétés de ces anticorps, comme leur intensité ou leur capacité à fixer le complément, sur l'échec des allogreffes rénales. Pour finir, nous avons étudié l’impact pronostic des formes indolentes de rejets ainsi que l’apport des nouvelles technologies d’analyses transcriptomique des biopsies de patients transplantés. Méthodes : Nous avons utilisé une approche en population, basée sur l’étude de larges cohortes de receveurs de greffes rénales. L’étude concomitante des données immunologiques et histologiques, nous a permis de corréler les caractéristiques des anticorps anti-HLA circulants aux phénotypes lésionnels. Résultats : Nous avons identifié et caractérisé 4 types distincts de rejet : les rejets vasculaires médiés par les lymphocytes T (9%) et par les anticorps (21%), non reconnus par les classifications internationales, et les rejets cellulaires (46%) et humoraux sans vascularite (24%). Le risque de perte de greffons est le plus important dans les cas de rejet vasculaire médié par anticorps. Les anticorps dirigés contre le donneur (DSA) fixant le complément induisent un phénotype histologique plus sévère, dominé par des lésions inflammatoires et plus de dépôts de la fraction C4d du complément dans les greffons. En leur présence, le risque de perte de greffons est augmenté de 3,7 fois (IC95 1,9-7,2). Les formes indolentes de rejet médié par les anticorps sont également associées à un risque accru de perte du greffon. L’utilisation d’approches moléculaires permet d’améliorer la stratification du risque au sein du groupe des patients présentant des rejets humoraux. Conclusion : Ce travail répond à un besoin clinique pressant dans le domaine de la transplantation, celui de déterminer l’impact clinique des anticorps anti-HLA et d’améliorer la stratification du risque immunologique en se basant sur leurs propriétés et l’utilisation de nouvelles technologies pour mieux caractériser l’activité et le stade des rejets humoraux. / Background : The alloimmune response induced by transplantation from a donor who differs genetically from the kidney recipient has always been the major obstacle to graft success. The present work aimed to improve characterization of kidney-allograft rejection phenotypes and identify how each one is associated with anti-HLA antibodies. We also sought to determine whether characteristics of these antibodies i.e., their levels or complementbinding ability, might play a role in kidney allograft failure. Finally, we evaluated the clinical relevance of indolent forms of ABMR and the clinical relevance of new genes expression technologies to stratify the kidney recipients at risk for failure. Methods : We used a population-based approach in precisely phenotyped cohorts of kidney recipients. The design of our study, which is based on the concomitant evaluation of immunologic and histologic data, permits a precise connection of circulating anti-HLA antibodies with a phenotype of graft injury. Findings : We identified four distinct patterns of kidney allograft rejection: T cell-mediated vascular rejection (9%), antibody-mediated vascular rejection (21%), not included in international classifications, T cell- (46%) and antibody-mediated rejection without vasculitis (24%). Risk of graft loss was 9.07 times (95CI 3.6-19.7) higher in antibody-mediated vascular rejection than in T-cell mediated rejections (p<0.0001). Patients with post-transplant complement-binding DSA had more severe graft injury phenotype with higher inflammation and increased deposition of complement fraction C4d. They have the poorest graft survival with 3.7 fold increased risk of graft loss (95CI 1.9-7.2). Subclinical ABMR is a truncated for of rejection associated with risk of kidney allograft failure. Gene expression assessment in kidney allografts with early ABMR improves classification of individuals at risk for kidney allograft loss. Conclusion : This work addresses the unmet need of the deleterious impact of anti-HLA antibodies and the improvement of risk stratification in kidney transplantation. Recognition of distinct phenotypes could lead to the development of new treatment strategies. Gene expression assessment appears useful to evaluate disease activity, disease state and prediction of failure.

Le pronostic est depuis longtemps un concept de base de la médecine. Hippocrate envisageait déjà le pronostic des maladies par l’étude des circonstances passées, l’établissement des faits présents, et enfin la prédiction des phénomènes à venir. Pour lui, tout l’art du pronostic était de savoir interpréter intelligemment ces informations, et ainsi moduler le pronostic en fonction de leur valeur relative. Une recherche à visée pronostique consiste toujours actuellement en l’examen des relations entre un état de santé connu au moment de l’investigation et un évènement futur. L’augmentation de l’espérance de vie implique que de plus en plus de personnes vivent avec une ou plusieurs maladies ou problèmes altérant leur santé. Dans ce contexte, l’étude du pronostic n’a jamais été aussi importante. Cependant, contrairement au domaine des essais cliniques randomisés dans lequel les recommandations CONSORT sont appliquées depuis plus de 20 ans et garantissent une recherche de qualité, la recherche pronostique commence seulement à se doter d’initiatives similaires. En effet, des recommandations TRIPOD ont été élaborées en 2015 et un groupe de travail, PROGRESS, s’est constitué en 2013 au Royaume-Uni et a fait le constat que les recherches a visée pronostique sont réalisées de façon très hétérogènes et malheureusement ne respectent pas toujours des standards de qualité nécessaires pour supporter leurs conclusions et garantir la reproductibilité des résultats (...) / Prognosis is historically a basic concept of medicine. Hippocrates already considered the prognosis of disease as the study of the past circumstances, the establishment of the present state of health and finally the prediction of future events. He presented the prognosis as the ability to interpret these elements and to adapt the prognosis regarding their relative values. Currently, the prognostic research is still based on the examination of the relationship between a well-established health condition at the time of the investigation and the occurrence of an event. The increase in life expectancy implies that more and more people are living with one or more diseases or with problems that can impair their health status. In this context, the study of the prognosis has never been more important. However, in comparison with the field of randomized clinical trials in which the CONSORT statement recommendations are implemented for more than 20 years in order to guarantee quality research, the prognostic research only begins to develop similar initiatives. Indeed, in 2015 the TRIPOD statement recommendations were provided and in 2013 a working group called PROGRESS was constituted in the United Kingdom and its members made the observation that prognostic researches are developed with considerable heterogeneity in the methodology used and unfortunately do not always meet the quality standards required to support their conclusions and their reproducibility (...)

Les alloanticorps anti-HLA sont dirigés vis-à-vis de différents épitopes des molécules du système HLA. Cette immunisation survient lors d'une transplantation d'organe, de transfusions sanguines ou d'une grossesse. On retrouve aussi ces anticorps, lorsque les techniques de détection sont sensibles, en l'absence de tout évènement immunisant. En transplantation d'organe, rénale en particulier, la présence d’anticorps anti-HLA, du fait des lésions de rejet humoral qu'ils induisent, constitue une des premières causes de perte de fonction des greffons à moyen et long terme. Néanmoins, les cellules lymphocytaires qui sont la source de ces anticorps anti-HLA demeurent mal identifiées.Dans la première partie de ce travail, nous avons étudié, dans une cohorte de patients en attente de transplantation rénale, la distribution des différentes sous-populations lymphocytaires B circulantes par cytométrie de flux en relation avec la nature des évènements immunisants vis-à-vis du système HLA, la présence et la diversité des anticorps anti-HLA. Nous avons étudié en parallèle les concentrations sériques de BAFF ("B cell activating factor belonging to the TNF family"), principal facteur impliqué dans la survie et la différenciation des lymphocytes B matures. Nous avons retrouvé une association entre la présence et la diversité des anticorps anti-HLA, et l'augmentation de la proportion de lymphocytes B naïfs activés Bm2, par rapport aux autres sous-populations lymphocytaires B, et indépendamment de l'existence d'évènements immunisants. Les concentrations sériques de BAFF étaient également associées positivement à la présence et à la diversité des anticorps anti-HLA. Ces données suggèrent que l'augmentation des lymphocytes B naïfs activés et des concentrations sériques de BAFF favorise le développement des anticorps anti-HLA à la suite d'un événement immunisant. A l'instar du mécanisme évoqué en auto-immunité, BAFF pourrait intervenir en présence de l'alloantigène en favorisant la survie de clones B alloréactifs.Dans la deuxième partie de notre travail, nous nous sommes intéressés plus particulièrement à l'implication des lymphocytes B mémoire alloréactifs dans la réponse humorale anti-HLA. Pour détecter les lymphocytes B mémoire circulants, nous avons utilisé un test de stimulation polyclonale permettant leur différenciation en plasmablastes puis nous avons recherché et étudié la spécificité des anticorps anti-HLA produits dans les surnageants de culture. Un premier résultat important a été la possibilité de détecter, chez les patients présentant des anticorps anti-HLA, des lymphocytes B mémoire alloréactifs circulants plusieurs années après un événement immunisant. En deuxième lieu, la présence de ces lymphocytes B mémoire était associée au nombre d'évènements immunisants. En effet, les patients ayant développé, en l'absence d'événement immunisant des anticorps anti-HLA - dont nous montrons par ailleurs le caractère potentiellement pathogène - n'ont pas présenté de lymphocytes B mémoire alloréactifs circulants. Enfin, à l'aide du logiciel HLAMatchmaker, nous avons montré que les anticorps produits par les lymphocytes B mémoire étaient dirigés contre un nombre restreint d'épitopes partagés par plusieurs antigènes HLA, ce qui suggère une oligoclonalité du contingent B mémoire alloréactif. Chez les mêmes patients, les anticorps anti-HLA circulants présentaient une diversité de spécificité plus large, étant dirigés contre de multiples épitopes HLA. Ces résultats suggèrent l'existence d'au moins deux types de réponse humorale vis-à-vis des alloantigènes HLA : l'une aboutissant à la production de lymphocytes B mémoire et de plasmocytes à la suite d'une réaction de centre germinatif T-dépendante, l'autre impliquant seulement des plasmocytes, possiblement issus de réponses extra-folliculaires. Les facteurs orientant vers l’un ou l’autre type de réponse sont encore mal définis mais pourraient impliquer la dose et la voie d'exposition aux alloantigènes. / Anti-HLA antibodies are directed against various epitopes of HLA molecules. They develop during organ transplantations, red cell transfusions or pregnancies. But anti-HLA antibodies are also detected with sensitive assays in the absence of any sensitizing event. In renal transplantation, anti-HLA antibodies, through the development of antibody-mediated rejection, represent the first cause of late allograft loss. Nevertheless, the mechanisms and the exact nature of B cells involved in anti-HLA antibodies synthesis are poorly understood.In a first part, we studied by flow cytometry in patients awaiting kidney transplantation the distribution of the different peripheral B cell subsets in relation with immunizing events, titer and diversity of anti-HLA antibodies. We also studied the serum levels of BAFF ("B cell activating factor belonging to the TNF family"), the main factor involved in survival and differentiation of mature B cells. We found an association between the presence and the diversity of anti-HLA antibodies, and the proportion of activated naive Bm2 B cells, at the expense of other subsets, independently of immunizing events. BAFF serum levels were also positively associated with the presence and the diversity of anti-HLA antibodies. These data suggest that the increase in activated naive B cells and in BAFF levels facilitate the development of anti-HLA antibodies, following an immunizing event. Similarly to what is observed in autoimmunity, BAFF could help to the positive selection of alloreactive B cell clones, in the presence of alloantigen.In a second part, we focused on the role of circulating alloreactive memory B cells in anti-HLA humoral response. To detect those alloreactive memory B cells, we used a polyclonal stimulation assay allowing the differentiation of memory B cells into plasmablasts and we studied the specificity of anti-HLA antibodies recovered from culture supernatant. A first important result was the detection, decades after an imunizing event, of specific alloreactive memory B cells, even in the absence of the antigen. The detection of those circulating alloreactive memory B cells was related to the strength of immunizing events, i.e. the number of different immunizing events in the history of patients. Indeed, patients with anti-HLA antibodies with no history of immunizing event had no circulating alloreactive memory B cells. Eventually, with HLAMatchmaker software, we showed that antibodies produced by memory B cells were directed against a limited number of epitopes shared by HLA antigens, which suggests an oligoclonality of the alloreactive memory B cell population. By comparison, serum antibodies displayed a greater diversity, with multiple epitopic specificities. These results suggest two distinct cellular arms of humoral response towards HLA epitopes: medullar plasma cells, involved in long term HLA antibodies synthesis, and memory B cells waiting for a recall response in the presence of the antigen. The factors involved in the choice of those two cellular fates are poorly understood but may involve dose and route of exposition to the alloantigen.