Characterization of the T-cell proliferative response to a purified glycopeptide antigen (GP-25) present on the Trypanosoma cruzi cell surface.

A glycoconjugate (GP-25) was previously purified from Trypanosoma cruzi and shown to be a major immunogenic constituent of the parasite cell surface, capable of inducing specific humoral responses in the vast majority of patients with Chagas' disease. In the present study, the T-cell proliferative response to GP-25 was studied in mice immunized with T. cruzi fractions or whole parasites. Recognition of GP-25 by proliferating T cells requires the participation of syngeneic, accessory spleen cells and is specifically blocked by anti-la antibodies. Furthermore, recognition of GP-25 is influenced by the MHC haplotype of accessory antigen-presenting cells. Short-term, GP-25-specific T-cell lines were used to demonstrate the specificity of anti-GP-25 T cells and to show that this glycoconjugate is not involved in T-cell cross-reactivity with heart antigens. T cells primed with nonpathogenic trypanosomatids are able to recognize the purified T. cruzi GP-25 molecule, indicating that T cells recognize a GP-25 epitope which is shared among trypanosomatids.