The role of IL-10 and IgG1 in the protection and granulomatous response in Schistosoma mansoni P24-immunized mice.

Previous work by our laboratory identified a fraction of Schistosoma mansoni soluble adult worm antigenic preparation, designated PIII, able to elicit significant in vitro cell proliferation, and lower in vitro and in vivo granuloma formation. In the present work, we investigated some biological activities of P24, an antigenic component of PIII. Immunization of mice with this antigen induced a significant protection degree against challenge infection and significant decrease in the hepatic granuloma formation. Pre-incubation of spleen cells from P24-immunized mice with S. mansoni antigens induced a significant increase of interleukin (IL)-10 levels, but not interferon-gamma, in the cell supernatants. In addition, mice immunized with different S. mansoni antigens and P24 displayed indistinguishable levels of IgG2a in response to anti-S. mansoni antigens, while IgG1 levels were significantly increased. Collectively, our results indicate that P24 might mediate protective anti-parasite immunity and downregulate granulomatous hypersensitivity to S. mansoni eggs in part by its ability to induce a higher production of IgG1 and IL-10.