Self and nonself stimulatory molecules induce preferential expansion of CD5(+) B cells or activated T cells of chagasic patients, respectively

It has previously been demonstrated that Trypanosoma cruzi-derived antigens (TRP) and human parasite-specific antibodies (Id) stimulate proliferation of cells from chagasic patients. More recently, we have shown that activate d T cells and CD5(+) B cells are present in elevated levels in the peripher al blood of chagasic patients. Upon in vitro exposure to these two differen t types of stimulatory molecules (TRP, Id), we now show that each of these elevated populations respond differentially to TRP or Id. We found that sti mulation with TRP led to preferential expansion of activated T cells, while Id preferentially stimulated CD5(+) B cells and CD8(+) T cells. Moreover, this expansion of CD5(+) B cells by Id was even more pronounced in cultures of cells from chagasic patients with the severe, cardiac form of the disea se, as compared to indeterminate patients. CD8(+) T cells comprise approxim ately 50% of the total T cells in cultures stimulated by Id while in TRP-st imulated cultures their frequency is proportionally lower. Since parasite a ntigens and antiparasite antibodies are always present in the host during t he chronic phase of the disease, they may also be involved with differentia l activation mechanisms of these cell populations in vivo.