A forte expressão do fator de crescimento endotelial vascular do tipo -C (VEGF-C) tem sido correlacionada com a presença de metástases linfonodais em carcinomas espinocelulares (CECs) de boca. O objetivo deste estudo consistiu em avaliar a expressão imuno-histoquímica do anticorpo anti-VEGF-C, nas células malignas de pacientes com CEC de boca em estádios iniciais, correlacionando-a com a ocorrência de metástases ocultas nos linfonodos cervicais e com o prognóstico dos pacientes. Um total de 87 pacientes com CEC de língua e assoalho de boca, estadiamento clínico I e II, tratados no Departamento de Cirurgia de Cabeça e Pescoço, do Hospital do Câncer A.C. Camargo, São Paulo, no período de 1968 a 2001, foram analisados quanto as características demográficas, clínicas, classificação pelo sistema TNM, tratamento e evolução clínica. Avaliou-se também o índice de malignidade tumoral histopatológico e a expressão imuno-histoquímica de VEGF-C foi comparada entre os CECs de boca sem (pN0) e com (pN+) comprometimento linfonodal (metástases ocultas). As probabilidades de sobrevidas global, livre de doença e específica por câncer dos pacientes com CEC, acumuladas nos períodos de cinco e dez anos, em relação a expressão tumoral de VEGF-C, foram calculadas pelo método de Kaplan-Meier. De sessenta e quatro pacientes submetidos ao esvaziamento cervical eletivo, quatorze deles (21,9%) apresentaram comprometimento linfonodal cervical histopatológico (metástase oculta). De acordo com os resultados, não houve correlação estatisticamente significativa entre a expressão de VEGF-C e as principais variáveis demográficas, clínicas, microscópicas e o índice histopatológico de malignidade tumoral (p=0,406), bem como com relação a ocorrência de metástases ocultas nos linfonodos cervicais (p=0,876). O único fator de prognóstico significativo para a sobrevida global (p=0,030) foi a ocorrência de metástase oculta comprovada por exame histopatológico. Concluiu-se que a expressão imuno-histoquímica isolada de VEGF-C nas células malignas não influenciou a evolução clínica e o prognóstico dos pacientes com CEC de língua e assoalho de boca nos estádios iniciais (I e II) e, portanto, o esvaziamento cervical eletivo permanece como uma intervenção terapêutica recomendada no tratamento destes pacientes. / The high expression of vascular endothelial growth factor-C (VEGF-C) has been correlated with the presence of lymph node metastasis from oral squamous cell carcinoma (OSCC). The purpose of this study was to evaluate the immunoexpression of VEGF-C antibody in malignant cells of patients in early stages of OSCC, and to correlate it with occult cervical lymph node metastasis and patients prognosis. Eighty seven patients with OSCC of tongue and floor of the mouth, clinical stage I and II, treated at the Department of Head and Neck Surgery and Otorhinolaryngology of Cancer Hospital A. C. Camargo, São Paulo, from 1968 to 2001, were included in this study. It was evaluated the demographical and clinical characteristics, TNM classification, treatment and clinical outcome. The histopathological malignancy index and immunoexpression of VEGF-C and their correlation with OSCC with (pN+) and without (pN0) positive lymph node (occult metastasis) were also evaluated. The overall and disease-free survival for OSCC patients for five and ten years related to VEGF-C tumor expression were calculated by Kaplan-Meier method. Among 64 patients that were submitted to elective neck dissection, 14 (21,9%) showed positive histopathological lymph node (occult metastasis). Our results did not show statistically significant difference for VEGF-C expression and main demographical, clinical, microscopical characteristics and histopathological malignancy index (p=0,406), as well as to occult neck metastasis (p=0,876). The occult lymph node metastasis was a prognostic factor for overall survival of patients with OSCC (p=0,030). In conclusion, the immunoexpression of VEGF-C in malignant cells per se did not influence the clinical outcome and prognosis of patients with OSCC of tongue and floor of the mouth in early stages (I and II). Therefore, elective neck dissection seems to be a therapeutical recommendation for the treatment of these patients.

INTRODUÇÃO: A presença de metástase cervical é um dos principais fatores prognósticos em pacientes com carcinoma epidermoide de laringe. A análise rotineira dos linfonodos não inclui a avaliação da reatividade linfonodal, nem pesquisa de micrometástases, podendo ser desprezada informações prognóstica relevantes neste grupo de pacientes. OBJETIVOS: Relacionar a reatividade linfonodal com a recidiva e mortalidade de pacientes com carcinoma epidermoide de laringe estadiados como pT3 e pT4, pN0, identificar através de marcadores imuno-histoquímicos (AE1/AE3, citoqueratina 7 e citoqueratina 5/6) a incidência de micrometástases e relacionar com o prognóstico dos pacientes. MÉTODO: Entre 2002 e 2005, foram selecionados 105 pacientes estadiados como pN0 com carcinoma epidermoide de laringe submetidos à laringectomia total e esvaziamento cervical seletivo dos níveis II, III e IV bilateralmente, com a maioria dos pacientes (69) submetidos à radioterapia adjuvante. Todos os linfonodos foram analisados conforme os padrões de reatividade: hiperplasia folicular (associada à resposta imune humoral), hiperplasia paracortical (associada à resposta imune celular), histiocitose sinusal, linfonodo normal e depleção linfonodal. Apenas os dois primeiros padrões são considerados como linfonodos estimulados e os demais como não estimulados. O padrão linfonodal mais frequente de cada caso foi considerado na análise da recidiva da doença e mortalidade. Todos os linfonodos foram submetidos à análise imuno-histoquímica com o clone de citoqueratinas AE1/AE3, e nos casos de positividade utilizou-se as citoqueratinas 5/6 e 7 para a diferenciação entre micrometástases e inclusões epiteliais benignas. RESULTADOS: Foram analisados um total de 3.648 linfonodos, com uma média de 34,7 linfonodos por paciente. O padrão de reatividade mais frequente foi a histiocitose sinusal (50 casos) seguido da hiperplasia paracortical (35 casos) e hiperplasia folicular (20 casos), não havendo relação entre esta análise e a recidiva (p = 0,98) ou mortalidade (p = 0,49). A resposta imune humoral esteve relacionada com maior mortalidade (p = 0,05), com sobrevida global em 5 anos de 76%, comparado a 60% de sobrevida no grupo com imunidade celular estimulada (log-rank = 0,05). A pesquisa imuno-histoquímica utilizando o clone de citoqueratinas AE1/AE3 foi positiva em 17 pacientes (16,2%) tendo esta análise relação com a recidiva da doença (p = 0,03) e com a mortalidade (p = 0,04). No grupo com AE1/AE3 positivo, a radioterapia associou-se a uma tendência de proteção à recidiva regional (p = 0,06). A citoqueratina 5/6 confirmou a presença de micrometástases em 4 (3,81%) casos e estas não apresentaram relação prognóstica com a recidiva (p = 0,66) e mortalidade (p = 0,66). A citoqueratina 7 diagnosticou inclusões epiteliais benignas em 11 (10,47%) casos. CONCLUSÕES: Pacientes com imunidade celular estimulada (hiperplasia paracortical) apresentaram menor mortalidade comparados aos pacientes com resposta imune humoral (hiperplasia folicular) (p = 0,05). A positividade na pesquisa com o clone de citoqueratinas AE1/AE3 apresentou relação com significância com a recidiva (p = 0,03) e com a mortalidade (p = 0,04). A incidência de micrometástases na pesquisa com citoqueratina 5/6 foi de 3,86% (4 casos de 105) e de inclusões epiteliais benignas foi de 10,47% (11 casos de 105). / INTRODUCTION: The presence of neck metastasis is one of the most important prognostic factors in patients with squamous cell carcinoma of the larynx. Immunohistochemical analysis for lymph node reactivity, micrometastasis and presence of benign epithelial inclusions are not included in routine anatomopathological exam, leading to potential missing of important prognostic information in this group of patients. OBJECTIVES: 1- To analyze if lymph node reactivity is associated with recurrence and mortality in patients with pT3/pT4, pNo SCCa of the larynx. 2- To identify, with the aid of hystochemical markers AE1/AE3, cytokeratin 7 and cytokeratin 5/6), the incidence of micrometastasis and benign intraepithelial inclusions and to evaluate the relationship of these findings with the patient`s prognosis. METHODS: One hundred and five patients with SCCa of the larynx underwent total laryngectomy and bilateral selective neck dissection of the levels II, III, and IV between 2002 and 2005. Sixty-nine patients also received postoperative radiotherapy. All 105 patients were N0 at the time of diagnosis. The lymph nodes were analyzed according to their reactivity pattern: Follicular hyperplasia (associated to humoral immune response), paracortical hyperplasia (associated to cellular immune response), sinusoidal histiocytosis, normal lymph node, lymphoid depletion. Only the he first two patterns are associated with stimulated lymph nodes. The predominant pattern on each case was recorded and the relationship between these patterns and tumor recurrence and mortality was assessed. All the lymph nodes were tested for cytokeratin AE1/AE3, and the positive cases were than tested for cytokeratin 5/6 and 7 to further differentiate micrometastasis from benign epithelial inclusions. RESULTS: A total of 3648 lymph nodes were analyzed (average of 34.7 lymph nodes/patient). The most common reactivity pattern was paracortical hyperplasia (49 cases), followed by sinusoidal histiocytosis (36 cases) and follicular hyperplasia (20 cases). There was no association between these different patterns and recurrence (p=0.98) or mortality (p=0.49). The humoral immune response was associated with increased mortality (p=0.005). The 5-year overall survival was 76%, compared to 60% on the stimulated cellular response group (LogRank=0.05). Seventeen patients (16.2%) were positive for cytokeratin AE1/AE3, and this was associated with tumor recurrence (p=0.03%) and mortality (p=0.004). In the positive cytokeratin group, the use of radiation therapy showed a tendency to protect against regional recurrence (p=0.06). The use of cytokeratin 5/6 confirmed the presence of micrometastasis in 4 cases (3.81%), but this finding was not associated with local recurrence (p=0.66) or mortality (p=0.66). Cytokeratin 7 has diagnosed benign epithelial inclusions in 11 cases (10.47%). CONCLUSION: Patients with stimulated cellular immunity experienced decreased mortality when compared to humoral immune response (p=0.05). AE1/AE3 positivity was significantly related to recurrence (p=0.03) and mortality (p=0.04). The incidence of micrometastasis was 3.86% (4 cases in 105 patients), and of benign ephitelia inclusions was 10.47% (11 cases in 105 patients).

Introdução: Atualmente a ressecção hepática é o melhor tratamento para metástases de câncer colorretal. Diversos fatores prognósticos foram estudados e muitos estudos têm demonstrado que metástases nos linfonodos hilares constituem um fator prognóstico adverso. Este estudo avaliou a frequência e as características do envolvimento linfonodal hilar microscópico, através de linfadenectomia sistemática, com pesquisa de micrometástases em pacientes submetidos à hepatectomia por metástases colorretais. Métodos: Os critérios de exclusão foram: irressecabilidade detectada no pré e intraoperatório, condições clínicas e fatores intraoperatórios que exigiam menor tempo cirúrgico, metástases linfonodais macroscópicas confirmadas por exame de congelação e menos de três linfonodos no produto da linfadenectomia. De 38 pacientes iniciais, 28 foram submetidos ressecção hepática em associação com linfadenectomia sistemática do hilo, apresentando três ou mais linfonodos dissecados. Os linfonodos negativos ao método convencional de hematoxilina e eosina foram avaliados através de cortes seriados com intervalos de 100 m associada à imunoistoquímica com anticorpos contra pancitoqueratinas humanas AE1/AE3. Resultados: Em média, 6,18 linfonodos foram dissecados por paciente. A linfadenectomia aumentou o tempo operatório em 48 minutos, no entanto, não houve morbimortalidade associada a este procedimento. Dois pacientes (7,2%) apresentaram metástase linfonodal microscópica ao exame convencional com hematoxilina e eosina. Quando aplicado os cortes seriados associados à imunoistoquímica, três pacientes adicionais (10,8%) foram identificados como portadores de micrometástases linfonodais. Conclusão: A frequência global de metástases microscópicas, incluindo micrometástases foi de 18%. Não houve correlação estatística entre outros fatores prognósticos e a presença de metástases microscópicas. A linfadenectomia sistemática associada à pesquisa de micrometástases ampliou a detecção de envolvimento linfonodal microscópico, contribuindo assim, com o estadiamento de doença extra-hepática / Introduction: Currently, hepatectomy is considered the best treatment of metastatic colorectal cancer. Several prognostic factors have been investigated, and many studies have shown that the involvement of regional lymph nodes at the hepatic hilum represents a negative prognostic factor. The present study investigated the frequency and characteristics of microscopic involvement of hilar lymph nodes, through systematic lymphadenectomy and analysis of micrometastases in patients undergoing hepatectomy due to colorectal metastases. Methods: Exclusion criteria were: no resectable disease detect in the pre or intra-operative; clinics conditions and intraoperative factors what required minor surgical time; macroscopic hepatic lymph node metastases, confirmed by frozen section and less of three lymph nodes resected for patient. Of the 38 patients, 28 underwent hepatic resection in association with systematic lymphadenectomy of the hepatic hilum, with three or more lymph nodes resected for patient. Lymph nodes considered negative by conventional hematoxylin and eosin staining were analyzed by serial sectioning with 100 m intervals and immunohistochemistry with antibodies to cytokeratins AE1/AE3. Results: In average, 6.18 lymph nodes were dissected per patient. Lymphadenectomy increased surgical time by 48 minutes in average, but no morbi-mortality was associated to the procedure. In two of the patients (7,2%), conventional hematoxylin and eosin analysis showed the presence of microscopic lymph node metastases. Immunohistochemistry analysis of serial sections allowed the identification of three other patients with lymph node micrometastases (10,8%). Conclusion: The overall frequency of microscopic metastases, including micrometastases, was 18%. No statistically significant relationships were observed between other prognostic factors and the presence of microscopic metastases. Systematic lymphadenectomy with inclusion of micrometastases protocols improved the detection of microscopic lymph node involvement, resulting in more accurate staging of extrahepatic disease

A forte expressão do fator de crescimento endotelial vascular do tipo -C (VEGF-C) tem sido correlacionada com a presença de metástases linfonodais em carcinomas espinocelulares (CECs) de boca. O objetivo deste estudo consistiu em avaliar a expressão imuno-histoquímica do anticorpo anti-VEGF-C, nas células malignas de pacientes com CEC de boca em estádios iniciais, correlacionando-a com a ocorrência de metástases ocultas nos linfonodos cervicais e com o prognóstico dos pacientes. Um total de 87 pacientes com CEC de língua e assoalho de boca, estadiamento clínico I e II, tratados no Departamento de Cirurgia de Cabeça e Pescoço, do Hospital do Câncer A.C. Camargo, São Paulo, no período de 1968 a 2001, foram analisados quanto as características demográficas, clínicas, classificação pelo sistema TNM, tratamento e evolução clínica. Avaliou-se também o índice de malignidade tumoral histopatológico e a expressão imuno-histoquímica de VEGF-C foi comparada entre os CECs de boca sem (pN0) e com (pN+) comprometimento linfonodal (metástases ocultas). As probabilidades de sobrevidas global, livre de doença e específica por câncer dos pacientes com CEC, acumuladas nos períodos de cinco e dez anos, em relação a expressão tumoral de VEGF-C, foram calculadas pelo método de Kaplan-Meier. De sessenta e quatro pacientes submetidos ao esvaziamento cervical eletivo, quatorze deles (21,9%) apresentaram comprometimento linfonodal cervical histopatológico (metástase oculta). De acordo com os resultados, não houve correlação estatisticamente significativa entre a expressão de VEGF-C e as principais variáveis demográficas, clínicas, microscópicas e o índice histopatológico de malignidade tumoral (p=0,406), bem como com relação a ocorrência de metástases ocultas nos linfonodos cervicais (p=0,876). O único fator de prognóstico significativo para a sobrevida global (p=0,030) foi a ocorrência de metástase oculta comprovada por exame histopatológico. Concluiu-se que a expressão imuno-histoquímica isolada de VEGF-C nas células malignas não influenciou a evolução clínica e o prognóstico dos pacientes com CEC de língua e assoalho de boca nos estádios iniciais (I e II) e, portanto, o esvaziamento cervical eletivo permanece como uma intervenção terapêutica recomendada no tratamento destes pacientes. / The high expression of vascular endothelial growth factor-C (VEGF-C) has been correlated with the presence of lymph node metastasis from oral squamous cell carcinoma (OSCC). The purpose of this study was to evaluate the immunoexpression of VEGF-C antibody in malignant cells of patients in early stages of OSCC, and to correlate it with occult cervical lymph node metastasis and patients prognosis. Eighty seven patients with OSCC of tongue and floor of the mouth, clinical stage I and II, treated at the Department of Head and Neck Surgery and Otorhinolaryngology of Cancer Hospital A. C. Camargo, São Paulo, from 1968 to 2001, were included in this study. It was evaluated the demographical and clinical characteristics, TNM classification, treatment and clinical outcome. The histopathological malignancy index and immunoexpression of VEGF-C and their correlation with OSCC with (pN+) and without (pN0) positive lymph node (occult metastasis) were also evaluated. The overall and disease-free survival for OSCC patients for five and ten years related to VEGF-C tumor expression were calculated by Kaplan-Meier method. Among 64 patients that were submitted to elective neck dissection, 14 (21,9%) showed positive histopathological lymph node (occult metastasis). Our results did not show statistically significant difference for VEGF-C expression and main demographical, clinical, microscopical characteristics and histopathological malignancy index (p=0,406), as well as to occult neck metastasis (p=0,876). The occult lymph node metastasis was a prognostic factor for overall survival of patients with OSCC (p=0,030). In conclusion, the immunoexpression of VEGF-C in malignant cells per se did not influence the clinical outcome and prognosis of patients with OSCC of tongue and floor of the mouth in early stages (I and II). Therefore, elective neck dissection seems to be a therapeutical recommendation for the treatment of these patients.

As Síndromes Mielodisplásicas (SMD) são doenças clonais, que se originam em células hemopoéticas totipotentes, com distúrbio na proliferação e perda da maturação celular gerando hipercelularidade na medula óssea (MO) e citopenias no sangue periférico (SP). As SMD ocorrem predominantemente em pacientes mais vellhos e estão associadas com um alto risco de progressão para leucemia mielóide aguda (LMA). A etiologia das SMD é deconhecida na maioria dos casos (de novo), porém 10% das SMD estão associadas ao uso de agentes xenobioticos, como os agentes antineoplásicos e solventes orgânicos (SMD secundária). Os pacientes com SMD apresentam diferente evolução clínica, embora todos sejam incuráveis. Alguns pacientes podem viver por uma década com apenas uma anemia enquanto outros apresentam uma sobrevida curta devido à uma rápida evolução para LMA. Diferentes aspectos biológicos da doença têm sido usados para dividir os pacientes em grupos e auxiliado nas decisões clínicas a serem tomadas em cada caso. A maioria dessas classificações levam em conta os subtipos morfológicos (classificação FAB) e os dados citogenéticos do clone mielodisplásico. Anormalidades cromossômicas são importantes marcadores das SMD. A maioria dos pacientes com esta síndrome apresenta aberrações citogenéticas que podem auxiliar no diagnóstico das SMD. Entretanto, algumas dessas aberrações podem ser correlacionadas com um mau prognóstico, como a monossomia do 7 e a trissomia do 8. Essas aneuploidias têm sido investigadas por estudos citogenéticos convencionais (bandamento G) e moleculares (\"FISH\" - Hybridization in situ Fluorescente). No intuito de se comparar a eficiência de ambas as técnicas e de se definir a freqüência e o significado prognóstico da monossomia do 7 (-7) e trissomia do 8 (+8) em SMD, foram estudados 28 pacientes com SMD-p (17 homens e 11 mulheres) por citogenética convencional (banda G) e molecular (\"FISH\" em intérfase), previamente a tratamento quimioterápico. Para compararmos o estudo cariotípico por bandamento G com o de \"FISH\", 19 pacientes foram estudados e a -7 foi detectada por \"FISH\" em seis pacientes e somente um deles o foi pela citogenética convencional. Os pacientes com -7 apresentaram uma menor sobrevida e um maior risco de transformação leucêmica. Cinco dos seis pacientes com -7 foram previamente classificados (FAB) como subtipos de mau prognóstico. Dois pacientes apresentaram +8, detectada por ambas as técnicas. Não houve diferença na sobrevida destes pacientes. Nossos resultados demonstraram que o \"FISH\" é uma técnica mais eficiente para detectar anomalias cromossômicas numéricas (-7) com importância prognóstica, especialmente em amostras pobres em metáfases, uma vez que \"FISH\" pode ser realizado em núcleos interfásicos. / Myelodisplastic Syndromes (MDS) are clonal disordes of hematopoietic stem cells characterized by ineffective hematopoiesis leading to blood cytopenias. They predominate in elderly patients and are associated with a high risk of progression to acute myelogenous leukemia (AML). The etiology of MOS is unknown in most cases (de novo) but about 10% of MDS are secondary to the use of xenobiotics, such as antineoplastic agents and organic solvents (secondary MDS). Though incurable, MDS patients have different clinical courses. Some patients can live for a decade with anemia being the only complaint whilst others present a very short term survival due to a rapid development of a treatment-refractory AML. Scales taking in account different biological aspects of the disease have been used in order to allocate patients in discrete risk levels. This risk stratification might help clinical decisions in a patient-by-patient basis. Most of these scales take in account the morphological subtype (FAB classification) and the cytogenetic status of the myelodysplastic clone. Chromosome abnormalities are very important markers of MDS. Most patients with this syndrome present cytogenetic aberrations which can be helpful in the diagnosis of SMD. Moreover, some of these aberrations have been correlated to a poorer prognosis, such as monosomy 7 and trissomy 8. These aneuploidies have been investigated by conventional (G-Banding) and molecular cytogenetic studies (In Situ Hybridization - FISH). In order to compare the efficiency of both techniques and to define the frequency and significance of monosomy 7 and trisomy 8 in MDS in a single institution population, chromosome studies of 28 patients were performed in metaphases by G-banding and in interphases by FISH (α satellite probes), before chemotherapy treatment. Chromosome studies by both techniques were obtained for 19 patients; monosomy 7 was detected by FISH in 6 patients; only one of these has been detected by conventional cytogenetics. Clinical follow-up of this monosomy 7 group patients disclosed short survival and increased risk for developing AML. Five out of the six patients with monosomy 7 were previously classified as the FAB subtypes of poor prognostic. 2 patients presented trisomy 8 in this series and were detected by both techniques. No difference in survival could be seen in these patients. Our results demonstrate that FISH is much more efficient to investigate chromosome numerical anomaly (at least monossomy 7) with prognostic relevance. This is specially true mainly when bone marrow samples lack metaphases since the studies can be performed in interphases cells.

The lymphatic system is an extensive vascular network responsible for the transport of fluid, immune cells, proteins and lipids. It is composed of thin-walled vessels, valves, nodes and ducts, which work together to collect fluid, approximately 4 L/day, from the interstitium transporting it back to the systemic network via the great veins. The failure to transport lymph fluid results in a number of disorders and diseases. Lymphedema, for example, is a pathology characterized by the retention of fluid in limbs creating extreme discomfort, reduced mobility and impaired immunity. In general, there are two types of edema: primary edema, being those cases that are inherited (i.e. genetic predisposition), and secondary edema, which develop post-trauma or injury of the lymphatic vessels. With the onset of breast cancer and radiation therapies, the prevalence of secondary edema is on the rise. Clinical studies have shown that up to 80% of women who undergo nodal-dissection surgery develop lymphedema in their arms within 3-5 years of the surgery. Unfortunately, there is no cure or remedy for lymphedema stemming from our lack of understanding of the lymphatic system. The goal of this study was to evaluate lymph flow both experimentally and analytically to better understand the mechanisms regulating lymph transport. In particular we investigated the effects of pressure, volume loads and valve resistance on lymphatic function in the rat mesentery. Our experimental results were then used to develop computational and constitutive models to emulate the dynamic behavior of lymph transport. Collectively, the data illustrate the mechanics of lymphatic contractility and lymph flow. In particular, lymph flow and pumping significantly increased post edemagenic stress in the rat model. Furthermore, lymphangions exhibited highly nonlinear pressure-diameter responses at low pressures between 3-5 cmH2O. These experimental results strongly suggest the regulation of lymph flow via changes in pressure, shear stress and vessel diameter. Furthermore, the computational and constitutive models from this study provide great insight into lymphatic function characterizing the mechanical properties of a single pumping unit (i.e. lymphangion). These models will serve as valuable tools to further lymphatic research.

<p>Mast cells, best known for their pathologic role in allergy, have recently been shown to have key roles in the initiation of adaptive immune responses. These cells are located throughout the body just beneath barriers separating host from environment, possess multiple pathogen recognition systems, and store large quantities of fully active inflammatory mediators. These key features make them uniquely situated to act as sentinels of immunity, releasing the very earliest alarm signals when a pathogen is present. As a testament to the importance of these cells, mast cell-deficient mice have suboptimal immune responses, and mast cell activators can act as potent adjuvants for experimental immunizations. Specifically, mast cells have been shown to enhance the number of naive lymphocytes in infection site-draining lymph nodes, and to encourage the migration of dendritic cells to responding lymph nodes.</p><p>Although infections usually occur at peripheral sites, adaptive immune responses are initiated in distant lymph nodes. Despite the distance, signals from the site of infection result in dramatic, rapid reorganization of the node, including massive recruitment of naive lymphocytes from the circulation and extensive vascular restructuring to accommodate the increase in size. How such signals reach the lymph node is not well understood.</p><p>When mast cells degranulate, in addition to releasing soluble mediators such as histamine, they expel large, stable, insoluble particles composed primarily of heparin and cationic proteins. The work presented herein demonstrates that these particles act as extracellular chaperones for inflammatory mediators, protecting them from dilution into the interstitial space, degradation, and interaction with non-target host cells and molecules. The data show clearly that mast cells release such particles, that they are highly stable, that they contain tumor necrosis factor (a critically important immunomodulator), and that they can traffic from peripheral sites to draining lymph nodes via lymphatic vessels. Furthermore, extensive biochemical characterization of purified mast cell-derived particles was performed. Finally, evidence is presented that such particles can elicit lymph node enlargement, an infection-associated phenomenon that favors the development of adaptive immunity, by delivering peripheral TNF to draining lymph nodes. </p><p>This signaling concept, that particles may chaperone signals between distant sites, also has important implications for adjuvant design. The evidence presented here shows that encapsulation of TNF into synthetic particles similar to mast cell-derived particles greatly enhances its potency for eliciting lymph node enlargement, an indication that adaptive immunity may be improved. This delivery system should ensure that more adjuvant arrives in the draining lymph node intact, where it would lead to changes favorable to the development of the immune response. Such a system would also facilitate the delivery of multi-component adjuvants that would act synergistically at the level of the lymph node when gradually released from microparticle carriers. An additional advantage of microparticle encapsulation is that vaccine formulations of this type may require much lower doses of expensive antigen and adjuvants.</p><p>The delivery of inflammatory mediators to lymph nodes during immune responses may be an important general feature of host defense. Although the action of mediators of peripheral origin on draining lymph nodes has been described before, this is the first demonstration of a specific adaptation to deliver such mediators. Not only is the characterization of mast cell-derived particles important to basic immunology, but mimicking this adaptation may also lead to improved therapeutics.</p> / Dissertation

No description available.

The lymphatic system has fundamental physiological roles in maintaining fluid homeostasis, immune cell trafficking and lipid transport from the small intestine to the venous circulation. Lymphatic vessels are the main functional organ responsible for the diverse transport roles the system plays. Unlike the blood vasculature, the lymphatic system does not have a central pump, such as the heart, and relies on a variety of factors to move lymph through. It was long thought that only external factors, such as skeletal muscle contraction and lymph formation, played a role in the functional transport capacity of these vessels. With the advancement of imaging capabilities (both hardware and software), it has become clear in the past two decades or so that the main factor in driving lymph transport is the ability of these vessels to intrinsically contract whereby each vessel is comprised of a chain of ‘mini pumps’ in series. The functional capacity of these vessels is thus now understood to be primarily determined by this pumping activity that has been shown to be regulated by various mechanical and biochemical cues. Lymphatic vessel dysfunction has been implicated in a variety of diseases including many lipid related pathologies and a neglected tropical disease known as lymphatic filariasis. While it has been possible to study the vessel function in the context of fluid drainage and immune cell trafficking, the capability to understand the role of lymphatic vessels in lipid transport has not been available due to the lack of experimental animal models and acquisition systems. As part of this thesis, we sought to develop an experimental animal model along with hardware and software tools to investigate the interplay between lymphatics and their lipid content. We report the first functional measurements of how vessels respond to elevated lipid loads. We further utilized our engineering expertise to develop an experimental platform allowing us to further understand the parasite known as B. malayi that migrates to and resides in lymphatic vessels.

Non-hematopoietic stromal cells (SCs) promote and regulate adaptive immunity through numerous direct and indirect mechanisms. SCs construct and support the secondary lymphoid organs (SLOs) in which lymphocytes crawl on stromal networks and inspect antigen-presenting cells for surface-display of cognate antigens. SCs also secrete survival factors and chemotactic cues that recruit, organize, and facilitate interactions among these leukocytes. They influence antigen access by secreting and ensheathing extracellular matrix-based conduit networks that rapidly convey small, soluble lymph-borne molecules to the SLO core. Furthermore, lymph node stromal cells (LNSCs) directly induce \(CD8^+\) T cell tolerance to peripheral tissue restricted antigens and constrain the proliferation of newly activated T cells in these sites. Thus, stromal-hematopoietic interactions are crucial for the normal functioning of the immune system. LNSCs are extremely rare and difficult to isolate, hampering the thorough study of their biology. In order to better understand these stromal subsets, we sorted fibroblastic reticular cells (FRCs), lymphatic endothelial cells, blood endothelial cells, and podoplanin \(^−CD31^−\) cells (double negative stromal cells; DNCs) to high purity from resting and inflamed murine lymph nodes. We meticulously analyzed the transcriptional profiles of these freshly isolated LNSCs as part of the Immunological Genome Project Consortium. Analysis of the transcriptional profiles of these LNSC subsets indicated that SCs express key immune mediators and growth factors, and provided important insights into the lymph node conduit network, FRC-specialization, and the DNC identity. Examination of hematopoietic and stromal transcription of ligands and cognate receptors suggested complex crosstalk among these populations. Interestingly, FRCs dominated cytokine and chemokine transcription among LNSCs, and were also enriched for higher expression of these genes when compared with skin and thymic fibroblasts, consistent with FRC-specialization. LNSCs that were isolated from inflamed lymph nodes robustly upregulated expression of genes encoding cytokines, chemokines, antigen-processing and presentation machinery, and acute-phase response molecules. Little-explored DNCs showed many transcriptional similarities to FRCs, but importantly did not transcribe interleukin-7. We identified DNCs as consisting largely of myofibroblastic pericytes that express integrin \(\alpha 7\). Together these data comprehensively describe the transcriptional characteristics of four major LNSC subsets isolated from resting and inflamed SLOs, offering many avenues for future study.