GLYCOINOSITOLPHOSPHOLIPIDS PURIFIED FROM TRYPANOSOMA-CRUZI STIMULATE IG PRODUCTION IN-VITRO

We have investigated the effects of glycoinositolphospholipid (GIPL) p urified from Trypanosoma cruzi on murine B cell activation. The GIPL n either stimulated any proliferative reponse by itself, nor affected th e blastogenesis induced by surface IgD cross-linking or LPS. On the ot her hand, the GIPL significantly stimulated both low and high density B cells to secrete IgM in vitro. The GIPL induced B cells to produce I gM when added in the presence of either the surface Ig cross-linker, a nti-delta-dextran, or a combination of IL-4 and IL-5. The T. cruzi-der ived GIPL also stimulated Ig class switch to IgG1 in cultures stimulat ed with GIPL, IL-4, and IL-5. The IgG1 secretion was comparable to tha t induced by LPS plus IL-4. Production of IgG3 was also detected and t he GIPL also potentiated the IgG3 production induced by LPS. The stimu latory effect of the T. cruzi-derived GIPL was mediated maily by its o ligosaccharide moiety. This isolated fraction induced a potent IgM sec retory response, compared with a much lower response induced by the is olated GIPL ceramide. Taken together, our data suggest that the stimul atory effect of the T. cruzi-derived GIPL on B cell activation could p lay a role on the conspicuous Ig production observed during infection of the host with T. cruzi.