| research-article |
Department of Immunology and Microbiology, Wayne State University School of Medicine, Detroit, Michigan 48201.
ABSTRACT
The pathological manifestations of schistosomiasis mansoni are primarily induced by circumovum hepatic granuloma formation and fibrosis. The growth and modulation of the granulomas are regulated by T lymphocytes and their products. In the present study, we isolated T-lymphocyte clones from lesions at the acute and chronic stages of murine infection. All of the T-cell clones were characterized by immunofluorescence as CD4+CD8- helper cells. Three T-cell clones derived from vigorous granulomas produced interleukin 2 (IL-2), IL-4, and gamma interferon (IFN-gamma) and were therefore classified as TH0-type T lymphocytes. Of the three clones derived from immunomodulated lesions, two produced IL-2 or IL-4 and/or IFN-gamma (TH0 type) and the other one did not produce IFN-gamma but did produce IL-4 and was therefore characterized as a TH2-type helper clone. The clones were further characterized by their responsiveness to soluble egg antigen fractions. The acute infection-derived clones responded to the lower-molecular-mass (60- to 66-kDa and 25- to 30-kDa) fractions, whereas the immunomodulated-granuloma-derived clones responded to the 60- to 66-kDa and higher-molecular-mass (70- to 90-, 93- to 125-, and > 200-kDa) fractions. Upon adoptive transfer into naive mice, both the TH0- and TH2-type clones were capable of inducing granuloma formation of similar magnitude around antigen-coated beads and/or freshly isolated parasite eggs. The present study revealed the presence of TH0-type precursor helper cells within the liver granulomas. The findings underscore the complexity of the granulomatous response at the T-cell level and demonstrate that both TH0- and TH2-type granuloma lymphocytes play a role in parasite egg-induced granuloma formation.
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