The role of different cytokines in the peripheral blood mononuclear cell (PBMC) proliferative response and in in vitro granuloma formation was evaluated in a cross-sectional study with patients with the different clinical forms and phases of Schistosoma mansoni infection, as well as a group of individuals "naturally" resistant to infection named normal endemic (NE). The blockage of IL-4 and IL-5 using anti-IL-4 and anti-IL-5 antibodies significantly reduced the PBMC proliferative response to soluble egg (SEA) and adult worm (SWAP) antigens in acute (ACT), chronic intestinal (INT) and hepatosplenic (HS) patients. Similar results were obtained in the in vitro granuloma formation. Blockage of IL-10 had no significant effect on either assay using PBMC from ACT or HS. In contrast, the addition of anti-IL-10 antibodies to PBMC cultures from INT patients significantly increased the proliferative response to SEA and SWAP as well as the in vitro granuloma formation. Interestingly, association of anti-IL-4 and anti-IL-10 antibodies did not increase the PBMC proliferative response of these patients, suggesting that IL-10 may act by modulating IL-4 and IL-5 secretion. Addition of recombinant IL-10 decreased the proliferative response to undetectable levels when PBMC from patients with the different clinical forms were used. Analysis of IFN-<FONT FACE="Symbol">g</font> in the supernatants showed that PBMC from INT patients secreted low levels of IFN-<FONT FACE="Symbol">g</font> upon antigenic stimulation. In contrast, PBMC from NE secreted high levels of IFN-<FONT FACE="Symbol">g</font>. These data suggest that IL-10 is an important cytokine in regulating the immune response and possibly controlling morbidity in human schistosomiasis mansoni, and that the production of IFN-<FONT FACE="Symbol">g</font> may be associated with resistance to infection.

Foi realizado um estudo sobre o T. sordida em ambiente silvestre em duas diferentes regiões do estado de Minas Gerais: Itapagipe (Triângulo), área de cerrado modificado para formação de campos de pastagem e agricultura, e Mato Verde (norte) uma área de transição entre a caatinga e o cerrado, profundamente desmatada nos últimos anos com a finalidade de expansão do cultivo de algodão. Em ambas as regiões, os principais ecotopos identificados corresponderam a buracos e cascas de árvores vivas ou mortas, onde a ocorrência de fontes de alimentação não é frequente. Neste ambiente, os triatomíneos utilizam-se de variadas fontes de alimentação; gambás parecem representar urna importante fonte de infecção. No norte de Minas, observou-se urna maior concentração de reservatórios e vetores em comparação com o Triângulo, o que pode explicar a maior taxa de infecção dos triatomíneos no norte. Maior atenção ao processo de domiciliação do T. sordida no norte de Minas Gerais é recomendada, onde, nos últimos anos, tem-se observado urna profunda intervenção do homem sobre o ambiente natural, paralelamente ao aumento da população deste triatomíneo nos peridomicílios.

A study was undertaken about T. sordida in the natural environment in two different regions of the state of Minas Gerais: Itapagipe (Triângulo), an area of cerrado modified by the formation of fields of pasture and agriculture, and Mato Verde (north) an area of transition between caatinga and cerrado with profound deforestation in the last years due to the expansion of cotton cultivation. In both regions the principal ecotopes identified were hollow trees and the bark of live or dead trees, where the occurrence of a food source is not frequent. In this environment, the triatomines utilize various food sources; opposums appear to represent an important source of infection. In the north of Minas, a greater concentration of reservoirs and vectors was observed than in the Triángulo which could explain the higher level of infection of the triatomines in the north. Close attention to the process of domiciliation of T. sordida in the north of Minas is recommended where an extensive intervention by man in the natural environment has occurred and where a rise in the population of triatomines in the peridomestic environment has been observed in recent years.