Growth hormone expression in stromal and non-stromal cells in the bursa of Fabricius during bursal development and involution: Causal relationships?

Growth hormone (GH) is expressed in the chicken bursa of Fabricius (BF), an organ that undergoes three distinct developmental stages: rapid growth (late embryogenesis until 6-8 weeks of age [w]), plateaued growth (between 10 and 15w), and involution (after 18-20w). The distribution and abundance of GH-immunoreactivity (GH-IR) and GH mRNA expression in stromal and non-stromal bursal cells during development, as well as the potential anti-apoptotic effect of GH in bursal cell survival were the focus of this study. GH mRNA expression was mainly in the epithelial layer and in epithelial buds at embryonic day (ED) 15; at 2w it was widely distributed within the follicle and in the interfollicular epithelium (IFE); at 10w it clearly diminished in the epithelium; whereas at 20w it occurred in only a few cortical cells and in the connective tissue. Parallel changes in the relative proportion of GH mRNA expression (12, 21, 13, 1%) and GH-IR (19, 18, 11, <3%) were observed at ED 15, 2w, 10w, and 20w, respectively. During embryogenesis, GH-IR co-localized considerably with IgM-IR, but scarcely with IgG-IR, whereas the opposite was observed after hatching. Significant differences in bursal cell death occurred during development, with 9.3% of cells being apoptotic at ED 15, 0.4% at 2w, 0.23% at 10w, and 21.1% at 20w. Addition of GH increased cultured cell survival by a mechanism that involved suppression (up to 41%) of caspase-3 activity. Results suggest that autocrine/paracrine actions of bursal GH are involved in the differentiation and proliferation of B lymphocytes and in BF growth and cell survival in embryonic and neonatal chicks, whereas diminished GH expression in adults may result in bursal involution.

Sorologia anti PGL-1 e risco de ocorrencia de hanseniase em area de alta endemicidade do Estado de Sao Paulo: quatro anos de seguimento / Anti PGL-1 serological and the risk of leprosy in a highly endemic area in the State of Sao Paulo, Brazil: four-year follow-up

Os testes sorologicos para diagnostico de hanseniase, usando o glicolipideo-fenolico-1 (PGL-I), considerando antigeno especifico do M. leprae, tem aberto algumas possibilidades de estudo do comportamento epidemiologico desta doença. Algumas questoes, como tempo de latencia da doença, infecçao subiclinica e importancia do contato intra-domiciliar (contatos) no controle da endemia puderam ser melhor analisadas usando este instrumental. Este estudo teve por objetivo verificar a existencia de associaçao entre a situaçao sorologica e a ocorrencia de hanseniase. Foram seguidas durante 4 anos, 6.520 pessoas com idade igual ou superior a 5 anos, submetidas no inicio do seguimento ao teste sorologico Anti PGL-1, pertencentes ao universo de 7.416 habitantes da area urbana de um municipio paulista caracterizado por elevada endemicidade de hanseniase. Foi identificado um grupo de 590 individuos soropositivos (9.0%). Foram diagnosticados, no periodo, 82 casos novos de hanseniase, 26 no grupo de soropositivos (441 casos novos/10.000 individuos) e 48 no de soronegativos (81/10.000). Entre os que nao fizeram sorologia, surgiram 8 casos novos (89/10.000). Procurou-se controlar, na analise, a condiçao de contato, dado que a taxa de soropositivo padronizada por idade e sexo era de 9.61% no grupo de contatos e 7.65% no de nao-contatos. Tomando-se aos de nao-contatos soronegativos como o grupo de "nao espostos", foram calculados os riscos relativos de adoecimento no periodo, a partir das taxas de detecçao padronizadas por idade, resultando no seguinte: os contatos ID soropositivos apresentaram a taxa de 1.704/10.000, 27 vezes maior que a dos "nao-expostos", igual a 63/10.000, os nao-contatos soropositivos e os contatos soronegativos apresentaram taxas, respectivamente, de 274 e 198/10.000 ambas maiores que as dos "nao-expostos" e iguais entre si. A soropositividade associou-se a elevaçao de 8,6 vezes do risco de hanseniase entre os contatos de 4,4 entre os nao-contatos. Na situaçao epidemiologica estudada, caracterizada por elevada endemicidade de hanseniase, 50% dos casos novos surgiram entre os nao-contatos soronegativos, ou seja, sem fonte de infecçao conhecida. Portanto o test anti-PGL-1 usado revela-se na pratica, de pouca aplicabilidade. Resta estudar ainda o comportamento da sorologia anti-PGL-1 em areas de media e baixa endemicidade par que se possa tirar conclusoes mais consubstanciadas sobre sua utilidade no controle da endemia

Role of membrane-bound IgM in Trypanosoma cruzi evasion from immune clearance.

We have recently described that Trypanosoma cruzi parasites of the reticulotropic Y strain increase their resistance to antibody-induced clearance during their interaction with the vertebrate host immune system. In the present study, we observed that trypomastigotes of the myotropic CL strain isolated from normal host also display an increased resistance to immune clearance when compared to parasites obtained from immunosuppressed donors. Through fluorescence-activated cell sorting analysis, we have observed that the high expression of membrane-bound IgM antibodies on Y and CL trypomastigotes correlates with their enhanced resistance to Ig-induced clearance. Trypomastigotes from normal mice were essentially refractory to the in vitro binding of immunoglobulins, showing that their membrane structures were completely covered by IgM antibodies. These findings suggest that this isotype does not efficiently mediate immune clearance. Moreover, membrane-bound IgM antibodies limited the amount of IgG attached to the parasite and, as a consequence, impaired efficient immune clearance. Through this mechanism, trypomastigotes of T. cruzi could increase their persistence in the bloodstream thus favoring parasite transmission to its hematophagous host vector in the early acute phase of the disease.

Anticorpos salivares anti-Streptococcus mutans em crianças com diferentes valores no índice de cárie / Antiboides anti-Streptococcus mutans in saliva of children with different values in dental caries index

O objetivo deste estudo foi avaliar o papel que o sistema imune secretório exerce sobre o desenvolvimento da cárie dentária. Foram selecionadas 49 crianças, com idades entre 3 e 5 anos que apresentavam somente a dentiçäo decídua. As crianças selecionadas foram divididas em três grupos de acordo com seu índice de cárie (ceos): crianças sem cárie (Grupo I), crianças com 1 ou 2 superfícies com lesäo de cárie (Grupo II) e crianças com cárie rampante (Grupo III). Níveis totais de IgA secretória salivar foram determinados através da técnica de ELISA, empregando-se componente anti-secretório como anticorpo de captura. Títulos de anticorpos salivares anti-S. mutans das classes IgG, IgM e IgA também foram avaliados através da técnica de ELISA, empregando-se extrato bruto da bactéria (S. mutans ATCC 25175). Foi estudado, também, o repertório de anticorpos salivares das classes IgA e IgG contra antígenos protéicos de um extrato de S. mutans em 14 crianças (5 do Grupo I, 5 do Grupo II e 4 do Grupo III) e 4 adultos através da técnica de Western blotting (7,5 por cento SDS - PAGE). Todos os resultados foram correlacionados a contagens de estreptococos do "grupo mutans" na saliva, realizadas através da técnica da micropipeta. Os níveis totais de IgA secretória na saliva, assim como os títulos de anticorpos salivares anti-S. mutans das classes IgA, IgM e IgG das crianças näo apresentaram diferenças significantes entre os 3 grupos analisados. Em relaçäo à contagem de estreptococos do "grupo mutans", o Grupo I apresentou um número significantemente menor de estreptococos do "grupo mutans" quando comparado aos outros dois grupos. Proteínas envolvidas na colonizaçäo do dente por S. mutans foram reconhecidas pelos anticorpos das classes IgA e IgG na maioria das amostras de saliva, como as de peso molecular de 39, 69, 74, 97 e 150 kDa. Outra proteína, a de 185 kDa, denominada antígeno I/II, foi reconhecida pelos anticorpos das classes IgA somente nas amostras de saliva de adultos. Em relaçäo aos anticorpos da classe IgG, o mesmo ocorreu, com exceçäo na amostra de saliva de uma das crianças do Grupo III. Nossos dados sugerem que o sistema imune secretório näo tem relaçäo direta com o desenvolvimento de lesöes cariosas. Entretanto, a imunologia da cárie dentária ainda näo é bem esclarecida e certamente merece mais estudos

Identification of IgM as the leprosy patient serum factor responsible for rapid sedimentation of formolized sheep erythrocytes.

The serum of some leprosy patients with impaired specific cellular immunity for Mycobacterium leprae causes rapid sedimentation of formolized sheep erythrocytes, a phenomenon known as the Rubino reaction. The Rubino factor was precipitated from positive sera by 5% (w/v) polyethylene glycol (PEG), bound to a concanavalin A (ConA)-Sepharose column and eluted with D-mannose, and was also eluted from a Mono Q column, pH 8.0, with 0.4 M NaCl. The Rubino factor was eluted in a volume which coincided with that of human serum IgM from a Sepharose 6 column. IgM was present in the preparation obtained by this sequence of chromatographic procedures. The correspondence of IgM with the Rubino factor was demonstrated by the following data: a) the Rubino factor was adsorbed to rabbit IgG antihuman IgM-agarose and the activity was recovered in the acid eluate of the column; b) the Rubino reaction was inhibited in the presence of rabbit antihuman IgM antibodies. This behavior was not observed when the same procedures were carried out using anti-alpha 2-macroglobulin antibodies as a control. The rapid sedimentation of formolized sheep red cells caused by the serum of lepromatous leprosy patients was not inhibited by phenolic glycolipid-I, suggesting that the IgM responsible for the Rubino reaction is not directed to this antigen which is specific for M. leprae. There was no correlation between the positivity of the Rubino reaction and the increase in total serum IgM levels observed in 42% of the lepromatous patients evaluated. The demonstration that the Rubino factor is an IgM now permits the identification of the epitope recognized by it, and this may be used as a tool to understand the specific cellular immune unresponsiveness which characterizes lepromatous leprosy.

Identification of IgM as the Leprosy Patient Serum Factor Responsible for Rapid Sedimentation of Formolized Sheep Erythrocytes

The serum of some leprosy patients with impaired specific cellular immunity for Mycobacterium leprae causes rapid sedimentation of formolized sheep erythrocytes, a phenomenon known as the Rubino reaction. The Rubino factor was precipitated from positive sera by 5% (w/v) polyethylene glycol (PEG), bound to a concanavalin A (ConA)-Sepharose column and eluted with D-mannose, and was also eluted from a Mono Q column, pH 8.0, with 0.4 M NaCl. The Rubino factor was eluted in a volume which coincided with that of human serum IgM from a Sepharose 6 column. IgM was present in the preparation obtained by this sequence of chromatographic procedures. The correspondence of IgM with the Rubino factor was demonstrated by the following data: a) the Rubino factor was adsorbed to rabbit IgG antihuman IgM-agarose and the activity was recovered in the acid eluate of the column; b) the Rubino reaction was inhibited in the presence of rabbit antihuman IgM antibodies. This behavior was not observed when the same procedures were carried out using anti-alpha 2-macroglobulin antibodies as a control. The rapid sedimentation of formolized sheep red cells caused by the serum of lepromatous leprosy patients was not inhibited by phenolic glycolipid-I, suggesting that the IgM responsible for the Rubino reaction is not directed to this antigen which is specific for M. leprae. There was no correlation between the positivity of the Rubino reaction and the increase in total serum IgM levels observed in 42% of the lepromatous patients evaluated. The demonstration that the Rubino factor is an IgM now permits the identification of the epitope recognized by it, and this may be used as a tool to understand the specific cellular immune unresponsiveness which characterizes lepromatous leprosy

Análise clínica das lesöes de retinocoroidite em crianças portadoras de toxoplasmose congênita / Clinical analysis of retinochoroiditis' lesions in children bearing congenital toxoplasmosis

Foram estudadas 96 crianças portadoras de toxoplasmose congênita, com idade variável entre 0 e 11 anos de vida, procedentes do HCL-UFMG, em Belo Horizonte. O diagnóstico foi estabelecido com base em exames clínicos e testes sorológicos. As lesöes de retinocoroidite foram analisadas sob o ponto de vista de sua incidência, lateralidade e distribuiçäo topográfica, correlacionando-as com a idade e o sexo dos pacientes. Essas lesöes estavam presentes em 77% (74) dos pacientes e predominavam na faixa etária de 0 a 4 meses. Näo houve preferência por nenhum dos sexos, sendo essas lesöes bilaterais em 68% (50) das vezes e unilaterais em 31% (23). O pólo posterior isoladamente foi a regiäo retiniana mais atingida, abrigando 52% (39) das lesöes. Trinta por cento (22) das retinocoroidites atingiram conjuntamente o pólo posterior e a regiäo periférica da retina, enquanto a regiäo periférica isoladamente foi atingida em 17% (13). Foi detectada uma nítida associaçäo entre as lesöes de retinocoroidite e a presença de estrabismo. Pode-se afirmar que essas lesöes retinianas säo constantes e frequentes na toxoplasmose congênita e, por isso mesmo, de considerável valor diagnóstico

Cuantificación del número y la función de las células mononucleares: RFc gamma de niños con desnutrición protéico-calórica (DPC) / Quantitative of number and the function of the mononuclear cells: Rfcy of malnutrition protein-caloric children (MPC)

Se han reconocido varios tipos de receptores de membrana en los linfocitos T, entre ellos se encuentran los receptores para las cadenas pesadas de inmunoglobulinas m* y gama, ellos participan en el reconocimiento de antígenos, además de ser marcadores de superficie para las subpoblaciones de linfocitos T. En la desnutrición proteico-calórica (DPC) se han observado alteraciones inmunológicas tanto en la inmunidad celular como en la inmunidad humoral, un ejemplo de ello es el incremento en las cifras de inmunoglobulinas o la disminución en la respuesta inmune celular a ciertos antígenos. Es posible que ésta alteración en la respuesta inmune esté asociada con una disfunción de las subpoblaciones de linfocitos T; por lo que nos propusimos investigar si existen diferencias entre el núnero, porcentaje y función de las subpoblaciones de linfocitos T entre lactantes sanos y con DPC. Observamos un aumento en el número y porciento de linfocitos T gama en niños con DPC, en relación con las células T de lactantes sanos (p<0.05). Sin embargo, hubo una mala respuesta de linfocitos T totales y subpoblación gama al estímulo con fitohemaglutinina en pacientes con DPC. Nuestros hallazgos, además de ser concordantes con lo reportado en el literatura, también sugieren que hay una disfunción en la subpoblación de células T gama.

Diagnóstico serológico (elisa) de borreliosis de lyme en un grupo humano de riesgo, Piura-Perú / Serological diagnosis (elisa) of lyme disease in a risk human group, Piura-Peru

Se realizó un estudio en 35 sueros de agricultores (mayor ó igual a 13 años), residentes en el distrito de Sapillica, provincia de Ayabaca, departamento de Piura, a fin de determinar anticuerpos IgM e IgG a Borrelia burgdorferi utilizando la prueba de ELISA (kig Sigma Diagnostic, MO-USA). 3 (8.57 por ciento) de los 35 sueros fueron positivos con valores de indice de 1.34, 1.78 y 1.08. El descarte de reacción cruzada con otras pruebas: Venereal Disease Research Laboratory, anticuerpos treponémicos fluorescentes (FTA), factor reumatoideo (RF), reacción de aglutinación microscópica (RAM) para leptospira interrogans y biflexa y anticuerpo antinucleares (ANA), fueron negativos en todos los sueros positivos a Borrelia burgdorferi, con excepción de una muestra que fue reactiva a FTA. Los agricultores investigados han sido considerados como grupo de riesgo para Borreliosis de Lyme, por el tipo de actividad laboral que realizan y por la presencia de Haemaphysalis leporispalustris e Ixodes en Piura. Los resultados obtenidos demostraron la presencia IgM e IgG a títulos mayores del valor positivo de corte e índice, que sugieren infección producida por Borrelia burgdorferi

Regulation of B cell antigen receptor signal transduction and phosphorylation by CD45.

CD45 is a member of a family of membrane proteins that possess phosphotyrosine phosphatase activity, and is the source of much of the tyrosine phosphatase activity in lymphocytes. In view of its enzymatic activity and high copy number, it seems likely that CD45 functions in transmembrane signal transduction by lymphocyte receptors that are coupled to activation of tyrosine kinases. The B cell antigen receptor was found to transduce a Ca(2+)-mobilizing signal only if cells expressed CD45. Also, both membrane immunoglobulin M (mIgM) and CD45 were lost from the surface of cells treated with antibody to CD45, suggesting a physical interaction between these proteins. Finally, CD45 dephosphorylated a complex of mIg-associated proteins that appears to function in signal transduction by the antigen receptor. These data indicate that CD45 occurs as a component of a complex of proteins associated with the antigen receptor, and that CD45 may regulate signal transduction by modulating the phosphorylation state of the antigen receptor subunits.

The role of complement in the stimulation of lysosomal enzyme release by polymorphonuclear leucocytes induced by immune complexes of IgG and of IgM.

The effect of complement components incorporated into precipitated immune complexes (IC) of IgG or of IgM on their capacity for stimulating lysosomal enzyme release from rabbit polymorphonuclear leucocytes was studied in vitro. We have found that: (i) complement causes an amplification in the stimulatory capacity of both classes of IC, the effect being dependent on the concentration of the IC, and higher for the IgM class; (ii) dose-effect experiments of competition by fluid-phase immunoglobulins have shown that IgG (in physiological or smaller concentrations) can inhibit greatly the stimulation by this class of immune complex; this inhibition can be prevented, however, by the presence of complement in the IC (a situation expected to occur in vivo); for IgM immune complexes there was no such competitive inhibition, so complement would not be necessary; (iii) the relevant complement factors must be located in the range C1-C3. These results help us to understand the importance of complement (besides the well-known generation of chemotactic factors) in the mechanisms of tissue injury produced by neutrophils in immune complex diseases.