PROTECTIVE EFFECT OF RSM28GST-SPECIFIC T-CELLS IN SCHISTOSOMIASIS - ROLE OF GAMMA-INTERFERON

Immunization with a single dose of 50 mu g of recombinant Schistosoma mansoni 28-kDa glutathione-S-transferase (rSm28GST) was able to induce a reduction in the worm burden, the number of eggs, and the degree of hepatic fibrosis as quantified by the measurement of collagen content in the liver of S. mansoni-infected mice. No relationship was found b etween anti-SmZSGST immunoglobulin G and immunoglobulin A titers and t he levels of protection obtained. Adoptive transfers of SmZSGST-specif ic total, CD4(+), or CD8(+) T cells reproduced the protective effect o btained with the recombinant molecule. Moreover, experiments studying in vivo T-cell depletion demonstrated that anti-CD4- or anti-CD8-treat ed mice showed a significant decrease in the protective effect conferr ed, suggesting a role of the two T-cell subpopulations in the expressi on of Sm28GST-mediated protection against hepatic damage. Sm28GST-spec ific cells produced little interleukin-4 and high levels of gamma inte rferon. Treatment of immunized mice with anti-gamma interferon antibod y totally suppressed the Sm2SGST-induced protective effect and led to the rapid death of infected animals, suggesting a role for this cytoki ne in the expression of the protective immunity obtained after immuniz ation with rSm28GST.