The influence of immunosuppressive drugs on neural stem/progenitor cell fate in vitro.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Objetivo: Uma série de casos sugerindo uma possível associação de pancreatite aguda (PA) e síndrome de ativação macrofágica (SAM) em lúpus eritematoso sistêmico pediátrico (LESP) foi reportada em dez crianças no nosso serviço, no entanto, não existem dados relativos à comparação entre PA e SAM em grandes populações de LESP e LES adulto (LESA). Métodos: Este estudo incluiu 362 pacientes LESP e 1.830 pacientes LESA. SAM foi diagnosticada de acordo com os critérios diagnósticos preliminares e PA de acordo com a presença de dor abdominal e/ou vômitos associados a um aumento de enzimas pancreáticas e/ou alterações radiológicas pancreáticas nos exames de ultrassonografia e/ou tomografia abdominal. Dados demográficos, características clínicas, SLEDAI-2K, SLICC/ACR-DI e tratamento foram avaliados. Resultados: A frequência de PA foi significantemente aumentada no LESP em comparação ao LESA [12/362 (3,3%) vs. 20/1830 (1,1%), p=0,003], com similar duração da PA nos dois grupos [22 (6-60) vs. 15 (4-90), dias, p=0,534]. As frequências de SAM (85% vs 30%, p=0,003) e óbito (31% vs. 0%; p=0,017) foram significantemente elevadas em crianças com PA comparadas com adultos com PA. Na análise dos pacientes com PA e SAM em comparação com os com somente PA sem SAM demonstrou que a idade dos pacientes com PA e SAM foi significantemente menor em comparação com aqueles sem SAM [15 (8,8- 55) vs. 33,5 (10,2-45,7) anos, p=0,007]. As frequências de febre (94% vs. 37%, p=0,001), leucopenia (82% vs. 19%, p=0,0001), trombocitopenia (65% vs. 19%, p=0,013), hipertrigliceridemia (87% vs. 42%, p=0,037) e hiperferritinemia (93% vs. 37%, p=0,011) foram significantemente aumentadas nos pacientes com PA e SAM comparados aos pacientes com somente PA. A concomitância de febre e hiperferritinemia foi significantemente mais freqüente no primeiro grupo (86% vs. 12%, p=0,0015). Conclusões: Este estudo forneceu novos dados que evidenciaram que SAM ocorreu na maioria dos LESP com PA com uma maior mortalidade em comparação com LESA. Além disso, foram identificados em pacientes com PA e SAM, um conjunto de parâmetros clínicos e laboratoriais associado com as duas complicações / Objective: We previously reported a case series of acute pancreatitis (AP) and macrophage activation syndrome (MAS) in childhood (cSLE) patients, however there are no data regarding the comparison of AP and MAS in large populations of cSLE and adult SLE (aSLE). Methods: This study included 362 cSLE and 1,830 aSLE patients. MAS was diagnosed according to preliminary diagnostic guidelines and AP according to the presence of abdominal pain or vomiting associated to an increase of pancreatic enzymes and/or pancreatic radiological abnormalities. Demographic data, clinical features, SLEDAI-2K, SLICC/ACR-DI and treatment were assessed. Results: Higher and significant frequency of AP in cSLE compared to aSLE patients [12/362(3.3%) vs. 20/1830(1.1%), p=0.003], with similar AP duration [22(6- 60) vs. 15(4-90) days, p=0.534]. MAS (85% vs. 30%, p=0.003) and death by MAS complication (31% vs. 0%, p=0.017) were significantly higher in children with AP compared with aSLE with AP. Further analysis of patients with AP and MAS compared with AP without MAS demonstrated that age in MAS patients was significantly lower compared with those without this complication [15(8.8-55) vs. 33.5(10.2-45.7) years, p=0.007]. The frequencies of fever (94% vs. 37%,p=0.001), leucopenia (82% vs. 19%,p=0.0001), thrombocytopenia (65% vs. 19%,p=0.013), hypertriglyceridemia (87% vs. 42%,p=0.037) and hyperferritinemia (93% vs. 37%,p=0.011) were also more frequently observed in AP patients with MAS compared in AP patients without MAS. Fever and hyperferritinemia concomitantly were more frequent in the former group (86% vs. 12%, p=0.0015). Conclusions: This study provides novel data demonstrating that MAS occur in the majority of cSLE with AP with a higher mortality compared to aSLE. In addition, we identified in AP patients, a cluster of MAS clinical and laboratorial parameters more associated with this complication

As infecções são a causa mais freqüente de morbidade e mortalidade observadas tanto aguda como tardiamente nos pacientes receptores de transplante pulmonar, o que pode estar diretamente relacionado a uma deficiência no transporte mucociliar do sistema respiratório. Nosso objetivo foi avaliar a influência de dois fatores envolvidos com o transplante pulmonar sobre o transporte mucociliar de ratos: a secção e anastomose brônquica e a imunossupressão pela ciclosporina A. Setenta e dois ratos foram distribuídos aleatoriamente em cinco grupos de acordo com: i) procedimento operatório e ii) terapia a que seriam submetidos. Os resultados mostram que houve uma diminuição significativa da Freqüência de Batimento Ciliar in situ, da Transportabilidade do Muco in vitro e da Velocidade de Transporte Mucociliar in situ medidos a partir do brônquio principal esquerdo dos ratos tratados com ciclosporina A (p<0,001). A Freqüência de Batimento Ciliar in situ dos brônquios operados mostrou-se diminuída também no grupo tratado com solução salina e sacrificado no 30º dia após a operação (p=0,001). Já a Velocidade de Transporte Mucociliar in situ mostrou uma diminuição significativa em todos os grupos submetidos à secção brônquica (p<0,001). Houve um efeito sinérgico entre a terapia com ciclosporina A e a secção brônquica, causando um prejuízo ao transporte mucociliar ainda maior do que quando analisados isoladamente. Concluímos que a Velocidade de Transporte Mucociliar in situ foi agudamente prejudicada após a secção brônquica e terapia imunossupressora pela ciclosporina A, havendo diminuição da freqüência de batimento dos cílios e alteração das propriedades viscoelásticas do muco respiratório. / Infections are the most common cause of early and late morbidity and mortality in lung transplant recipient, and can be directly related to impaired mucociliary transport. Our aim was to assess the influence of bronchial section and imunossupression on mucociliary transport in rats. Seventy two rats were randomly distributed in five groups according to i) surgical procedure and ii) drug therapy. There was a significant impairment on Ciliary Beating Frequency in situ, Mucus Transportability Rate in vitro and Mucociliary Transport Speed in situ from operated bronchus of cyclosporine A-treated rats (p<0.001). Ciliary Beating Frequency from operated bronchus was also impaired in saline-treated rats that were killed on 30th postoperative day (p=0.001). Mucociliary Transport Speed was impaired in all bronchi underwent to section (p<0.001). We conclude that bronchial section and cyclosporine therapy impaired all factors analyzed. Also there was a synergic effect between cyclosporine therapy and bronchial section on ciliary beating frequency.

Introdução: Os corticosteróides e a persistência do hiperparatiroidismo são os principais fatores envolvidos na perda de massa óssea de pacientes ao longo do primeiro ano de transplante renal (TR).Os estudos no TR tardio são muito contraditórios,uma vez que as populações avaliadas foram heterogêneas.Os resultados revelaram diminuição da formação e aumento da reabsorção óssea além de defeito na mineralização. Objetivos: 1) Avaliar o metabolismo mineral e o tecido ósseo após o segundo ano de transplante renal em pacientes com boa função do enxerto e sem fatores de risco para a perda de massa óssea. 2) Determinar os possíveis fatores determinantes da massa e remodelação óssea. 3) Estudar a atividade funcional dos osteoblastos in vitro. Métodos: Avaliamos 27 pacientes transplantados renais com idade entre 18 a 50 anos (36,4 + 8,9 anos) boa função do enxerto (clearance de creatinina > 50ml/min), recebendo o mesmo esquema imunossupressor desde o início do TR e doses mínimas de corticosteróides. Todos apresentavam função gonadal normal. Excluímos os pacientes submetidos a paratiroidectomia, que receberam tratamento prévio com cálcio, vitamina D ou bisfosfonato. Os pacientes foram submetidos a avaliação clínica, laboratorial, densitometria óssea (DO) e biópsia óssea da crista ilíaca. Foi realizado cultura de células de osteoblastos, obtidos da biópsia óssea, e analisada a taxa de proliferação celular e expressão de fosfatase alcalina. Resultados: A hipercalcemia esteve presente em 40% dos pacientes, hipofosfatemia em 26% e 15% apresentavam acidose metabólica. Nos pacientes em uso de tacrolimus (FK) os níveis de fósforo sérico foram significativamente inferiores aos do grupo ciclosporina (CSA) (p=0.019). Os níveis de PTH estavam adequados para a função renal na maioria dos pacientes, entretanto 30% tinham níveis superiores a 65 pg/ml. Os níveis de osteoprotegerina (OPG) (85%) e deoxipiridinolina (DPD) (95%) estavam elevados na maioria dos pacientes Quanto aos valores de 25(OH) D (25,4 ± 8,7 ng/ml) os mesmos encontravam-se reduzidos em 63% dos pacientes. Não houve perda óssea significativa pela análise do score Z lombar (-0,9 ± 1,5) e do femur (-0,8 ± 1,1), porém em 26% dos pacientes diagnosticamos osteoporose pela densitometria. A média do volume ósseo estava dentro da normalidade, porém, 30% dos pacientes apresentavam redução do BV/TV. Nossos pacientes tinham aumento da separação e diminuição do número das trabéculas ósseas, além de aumento das superfícies osteóide, osteoblástica, de reabsorção e osteoclástica. Em cerca de 60% dos pacientes observamos diminuição da taxa de formação óssea e em 85% deles da superfície mineralizante. Retardo na mineralização óssea foi observado em 46% dos pacientes. Insuficiência de 25(OH) D cursou com defeito de mineralização em todos os pacientes. Os osteoblastos em cultura apresentaram elevada taxa de proliferação apesar da diminuída expressão de fosfatase alcalina. A proliferação celular foi maior no grupo FK que CSA (p=0,0007). O PTH foi o determinante independente do fósforo sérico (p=0,042), DMO lombar (0,044) e volume osteóide (p=0,001). Conclusões: Após dois anos de transplante renal estável no qual, os principais fatores de risco para perda de massa óssea, foram afastados nenhum paciente apresentava tecido ósseo normal. Encontramos, predominantemente, diminuição da formação, aumento da reabsorção óssea e defeito de mineralização caracterizando a presença de doença mista. Esses achados se devem provavelmente à hipofosfatemia, persistência do hiperparatiroidismo, insuficiência de 25(OH) D e a ação de drogas imunossupressoras / We evaluated bone mineral metabolism and histology from twenty seven late kidney transplanted patients, as well as osteoblastic activity in vitro obtained from bone biopsies. Patients were young, with stable graft function, in use of minimal immunosuppressive drugs doses and without known risk factors for bone loss. Hypercalcemia was found in 40%, whereas 26% had hypophosphatemia, 30% hyperparathyroidism and 63% 25-OH vitamin D insuficiency. Bone volume was decreased in 30% of them with elevated bone resorption in the majority, low bone formation in 60% and mineralization defect in 46%. Osteoblastic cells on culture expressed less alkaline phosphatase despite high proliferation rate. After a high restrictive selection of the patients, they still presented mixed bone diseased. These findings are probably related to immunosuppressive drugs, persistence of hyperparathyroidism and 25-OH vitamin D insuficiency

Em estudos anteriores, mostramos que uma nanoemulsão artificial (NEm) de composição semelhante à da lipoproteína de baixa densidade se liga a receptores de lipoproteínas de baixa densidade após sua injeção na corrente sanguínea. Como tais receptores estão superexpressos em células com altas taxas de proliferação, como ocorre no cancer e na aterosclerose, a NEm pode ser utilizada como veículo para direcionar drogas a estas células, diminuindo sua toxicidade e aumentando sua ação farmacológica. Recentemente, reportamos que a associação de um derivado do agente antiproliferativo paclitaxel, o oleato de paclitaxel (OPTX) à NEm reduziu em 60% a área lesionada de aortas de coelhos submetidos à dieta rica em colesterol. Neste estudo, testamos o efeito sinérgico da terapia combinada do OPTX-NEm com um derivado do metotrexato, o di-dodecil metotrexato (DMTX), também associado à NEm. O MTX, além de sua ação antiproliferativa, também possui propriedades imunossupressoras. Coelhos machos da raça Nova Zelândia foram submetidos à dieta enriquecida com 1% de colesterol durante 8 semanas. A partir da quinta semana de consumo da dieta, 8 animais foram injetados semanalmente com solução salina por via endovenosa (grupo controle) e 8 receberam o tratamento combinado de OPTX-NEm (4mg/Kg) com DMTX-NEm (4mg/Kg), por 4 semanas. Ao final das 8 semanas, os animais foram sacrificados. As aortas dos animais foram retiradas, abertas longitudinalmente, fixadas em formalina tamponada a 10% e coradas com Escarlate R para a análise macroscópica da lesão. Os arcos aórticos foram seccionados em fragmentos de 5mm, embebidos em parafina e os cortes realizados foram corados com hematoxilina-eosina, para a determinação da área das camadas íntima e média. O tratamento combinado de OPTX-NEm com DMTX-NEm reduziu a área das lesões em 82%, em comparação ao grupo controle, e a razão da área da lesão/área total diminuiu de 0,82±0,08 para 0,08±0,06 (p<0,01). Por meio das avaliações da variação do consumo de ração, peso corporal e contagem de leucócitos totais (p>0,05), pode-se afirmar que os tratamentos não apresentaram toxicidade significativa, exceto pela queda na contagem de eritrócitos (p<0,05). Como conclusão, a quimioterapia combinada de OPTX e DMTX associados à NEm como veículo mostrou-se eficaz na redução da área de lesão aterosclerótica em coelhos e a toxicidade relacionada aos fármacos foi nitidamente reduzida. / In previous studies we have shown that an artificial nanoemulsion (NEm) that resemble LDL composition are taken-up by LDL receptors after injection into the bloodstream. As those receptors are upregulated in cells with higher proliferation rates, as occurs in cancer and atherosclerosis, NEm can be used as vehicle to direct drugs against those cells, diminishing toxicity and increasing pharmacological action. Recently, we reported that association of antiproliferative agent paclitaxel derivative, paclitaxel oleate (OPTX) to NEm reduced by 60% the lesion area of cholesterol-fed rabbits. In this study, the combined chemotherapy of OPTX-NEm with a methotrexate derivative, di-dodecil methotrexate (DMTX), also associated with NEm, was tested for synergistic effects. MTX, besides antiproliferative action, has also immunosuppressant properties. Male New Zealand rabbits were fed a 1% cholesterol diet for 60 days. Starting from day 30, 8 animals were treated with 4 weekly I.V. saline solution injections (control group) and 8 with combined OPTX-NEm (4 mg/kg) plus DMTX-NEm (4 mg/kg) for additional 30 days. On day 60, the animals were sacrificed for analysis. Aorta was excised, open longitudinally, placed in 10% buffered formalin and stained in Scarlet R for lesion macroscopic analysis. Segments of 5mm of the aortic arch were embedded in paraffin and sections were taken and stained in hematoxylin-eosin for intima and media area measurement. In comparison with controls, treatment with combined OPTX-NEm plus DMTX-NEm reduced the lesion area by 82% and the lesion/total area ratio was decreased from 0,82±0,08 to 0,08±0,06 (p<0.01). Except for decrease in erythrocyte count (p<0.05), treatments were devoid of significant toxicity, as evaluated by food intake, body weight and leucocyte count (p>0.05). In conclusion, this novel approach consisting in combined chemotherapy of OPTX and DMTX using NEm as a drug-targeting vehicle showed effective lesion area regression in rabbits and marked toxicity reduction.

L’objectif de cette thèse était d’améliorer les connaissances fondamentales sur le tissu adipeux, organe qui est au cœur de la pratique des chirurgiens plasticiens. En effet, ce tissu peut être transplanté de façon autologue afin de combler une perte de substance (rôle volumateur des adipocytes) mais également servir à des fins de régénération tissulaire en lien avec les cellules de la fraction vasculaire stromale (FVS) et tout particulièrement des cellules stromales mésenchymateuses (CSM). Ces cellules s’obtiennent après lipoaspiration du tissu par une digestion enzymatique de la graisse obtenue. Il s’avère que les connaissances disponibles sur ces CSM sont essentiellement issues d’études in vitro après une phase de culture cellulaire plus ou moins longue et ainsi les propriétés in vivo sont mal connues. Ce travail a donc consisté à caractériser l’hétérogénéité du compartiment stromal natif du tissu adipeux obtenu après digestion enzymatique. Nous avons isolé deux populations stromales natives distinctes : les ASC (CD34+), en grande majorité, et des cellules péricytaires (CD146+). Ces 2 types cellulaires différaient dans leurs phénotypes, leurs potentiels de clonogénécité et leurs propriétés immunomodulatrices in vitro et in vivo. Nous avons ensuite comparé la digestion enzymatique du tissu aux techniques de digestion mécanique utilisable au sein de nos blocs opératoires. Nous avons démontré que ces nouvelles techniques permettaient bien de produite les cellules de la FVS dont des CSM, cellules particulièrement intéressante pour des gestes de régénération tissulaire. De plus, l’ensemble des techniques de laboratoire acquise au cours de ce travail nous ont permis d’investiguer le rôle des techniques de lipoaspiration utilisé en chirurgie plastique sur le tissu adipeux. Nous avons démontré par cytométrie de flux et par immunofluorescence in situ qu’une partie de la trame microvasculaire était conservée. L’ensemble de ces résultats viennent s’ajouter aux données cliniques démontrant que la lipoaspiration du tissu est un geste permettant d’être plus conservateur pour le tissu et pourrait expliquer des taux de complications moindre après chirurgie de contour de la silhouette. / The aim of this work was to improve the knowledge on adipose tissue, organ that is at the heart of the practice of plastic surgeons. Indeed, this tissue can be transplanted autologously in order to fill a defect (volumizing role of the adipocytes) but also to be used for tissue regeneration in connection with the cells of the stromal vascular fraction (SVF) and especially the mesenchymal stromal cells (MSCs). These cells are obtained after liposuction of the tissue by enzymatic digestion of the extracellular matrix. It turns out that the knowledge available on these CSM is essentially derived from in vitro studies after a cell culture phase and thus the in vivo properties are poorly known. This work consisted in characterizing the heterogeneity of the native stromal compartment of adipose tissue obtained after enzymatic digestion. We isolated two distinct native stromal populations: the ASC (CD34 +), for the most part, and the pericyte cells (CD146 +). These 2 cell types differed in their phenotypes, their clonogenecity potentials and their immunomodulatory properties in vitro and in vivo. We then compared the enzymatic digestion of the tissue with the techniques of mechanical digestion usable within our operating room. We have demonstrated that these new techniques made it possible to produce the cells of the FVS including MSC, cells particularly interesting for regenerative surgery. In addition, all the laboratory techniques acquired during this work allowed us to investigate the role of liposuction techniques used in plastic surgery on adipose tissue. We have demonstrated by flow cytometry and confocal microscopy, that part of the microvasculature framework is conserved after liposuction. All of these results are in addition to clinical data demonstrating that liposuction of the tissue is a gesture to be more conservative for the tissue and could explain lower rates of complications after contour surgery.

La plupart des virus ont développé des mécanismes de résistance ou de suppression du système immunitaire pour parvenir à infecter durablement leur hôte. Ces mécanismes demeurent encore imparfaitement connus. Un domaine immunosuppresseur (IS) a été identifié au niveau de la région transmembranaire des protéines d’enveloppe des rétrovirus endogènes ou infectieux. Ce domaine hautement conservé a été décrit par exemple comme inhibant l’activation lymphocytaire. Dans le laboratoire, il a été caractérisé en particulier via des expériences de rejet de cellules tumorales in vivo, ce qui a permis de définir des mutations inactivatrices. Afin de mieux comprendre les mécanismes de résistance des rétrovirus au système immunitaire, mes travaux de thèse ont porté sur l’identification de la ou des protéines capables d’interagir avec le domaine IS. Plusieurs approches cellulaires et moléculaires ont été développées, basées pour la plupart sur l’utilisation de sondes fluorescentes obtenues par synthèse chimique, constituées des domaines IS provenant de différents rétrovirus. Dans un premier temps, les cellules du système immunitaire qui lient les protéines virales ont été identifiées : les lymphocytes B et les cellules myéloïdes (monocytes, cellules dendritiques et macrophages). Dans un second temps, des expériences de co-immunoprécipitation et de chromatographie d’affinité couplées à la spectrométrie de masse ont été réalisées dans le but d’identifier sur ces cellules les protéines membranaires responsables de ces liaisons. Plusieurs agents de couplages chimiques ont été utilisés afin de maintenir les liaisons domaine IS - protéine de faibles affinités. En raison de résultats non-reproductibles obtenus au cours de ces expériences, des tests de liaison du domaine IS sur des cellules transfectées avec des banques d’ADNc, ou lors d’expériences de double hybride ont été réalisées. Ces deux approches ont permis d’identifier des protéines membranaires potentiellement impliquées dans la liaison du domaine IS : les protéines X1 et X2. Les co-transfections de vecteurs d’expression du domaine IS et de X2 ont mis en évidence des interactions protéiques au cours d’expériences de co-immunoprécipitation et de microscopie confocale, en particulier avec le domaine IS du rétrovirus HIV-1. Concernant X1, sa transfection induit la liaison cellulaire des domaines IS de HERV-W et MLV. En revanche, aucune interaction directe entre X1 et le domaine IS n’a pu être démontrée, notamment dans des expériences de co-immunoprécipitation et de microscopie confocale.La découverte des protéines membranaires qui interagissent avec le domaine IS demeure un enjeu critique pour la compréhension des voies de signalisation et de transcription qui permettent aux rétrovirus d’exercer leur effet sur le système immunitaire, l’objectif de ces travaux étant d’identifier à terme des nouvelles cibles thérapeutiques.En conclusion, même si des travaux complémentaires demeurent nécessaires, les protéines X1 et X2 pourraient contribuer à l’immunosuppression rétrovirale. / Most viruses have developed mechanisms of resistance or suppression of the immune system to achieve lasting infection of their host. These mechanisms are still imperfectly known. An immunosuppressive (IS) domain has been identified in the transmembrane region of envelope proteins of endogenous or infectious retroviruses. This highly conserved domain has been described, for example, as inhibiting lymphocyte activation. In the laboratory, it has been characterized by tumor cell rejection experiments in vivo, which has made it possible to define inactivating mutations. In order to better understand the mechanisms of resistance of retroviruses to the immune system, my thesis focused on the identification of the protein(s) interacting with the IS domain. Several cellular and molecular approaches have been developed, based for the most part on the use of fluorescent probes obtained by chemical synthesis, consisting of IS domains from different retroviruses. At first, immune system cells that bind viral proteins have been identified: B cells and myeloid cells (monocytes, dendritic cells and macrophages). In a second step, co-immunoprecipitation and affinity chromatography coupled to mass spectrometry were performed to identify on these cells the membrane proteins responsible for these bonds. Several chemical coupling agents have been used to prevent detachment of low affinity binding between proteins and the IS domain. Due to non-reproducible results obtained during these experiments, IS domain binding assays on cells transfected with cDNA libraries, or in double hybrid experiments were performed. These two approaches made it possible to identify membrane proteins potentially involved in the binding of the IS domain: the X1 and X2 proteins. Co-transfections of IS domain and X2 expression vectors demonstrated protein interactions in co-immunoprecipitation and confocal microscopy experiments, particularly with the IS domain of the HIV-1 retrovirus. Concerning X1, its transfection induces binding of the IS domains of HERV-W and MLV on cells membrane. On the other hand, no direct interaction between X1 and the IS domain could be demonstrated, especially in co-immunoprecipitation and confocal microscopy experiments.The discovery of membrane proteins that interact with the IS domain remains a critical issue for understanding the signaling and transcription pathways that allow retroviruses to exert their effect on the immune system, the aim of this work being to identify new therapeutic targets.In conclusion, although further work is still needed, the X1 and X2 proteins may contribute to retroviral immunosuppression.

The influence of immunosuppressive drugs on neural stem/progenitor cell fate in vitro.

Indiana University-Purdue University Indianapolis (IUPUI) / Platelet-activating Factor (PAF) stimulates various cell types by the activation of the G-protein coupled PAF-receptor (PAFR). Systemic PAFR activation induces an acute pro-inflammatory response, as well as delayed systemic immunosuppressive effects in vivo. De novo enzymatic PAF synthesis and degradation are closely regulated, but oxidative stressors, such as UVB, and cigarette smoke, can generate PAF-like species via the oxidation of membrane lipids in an unregulated process. Mast cells (MCs) and the PAFR have been shown to be necessary to mediate the resulting systemic immune suppression from oxidative stressors. The work herein implicates pro-oxidative chemotherapeutics, such as melphalan and etoposide, in mediating augmentation in tumor growth by inducing the generation of PAFR agonists via the oxidation of membrane lipids. This work also demonstrates the role of MCs and MC-released mediators in PAFR systemic immunosuppression. Through a contact hypersensitivity (CHS) model, the MC PAFR was found to be necessary and sufficient for PAF to mediate systemic immunosuppression. Additionally, activation of the MC PAFR seems to induce MC histamine and prostaglandin E2 release. Furthermore, by transplanting histamine- or COX-2-deficient MCs into MC-deficient mice, MC-derived histamine and prostaglandin release were found to be necessary for PAF to induce systemic immunosuppression. Lastly, we have evidence to suggest that prostaglandin release modulates MC migration to draining lymph nodes, a process necessary to promote immunosuppression. These studies fit with the hypothesis that MC PAFR activation mediates PAFR systemic immunosuppression in part by histamine and prostaglandin release.