Reactivity of chagasic sera with crude and highly purified glycosphingolipid fractions from Trypanosoma cruzi epimastigotes

The reactivities of sera from patients with Chagas disease or from T. cruzi‐immunized rabbits with two different lipid preparations of T. cruzi were assessed using epimastigote antigens. Serum reactivities were determined using a quantitative enzyme‐linked immunosorbent assay (ELISA). Antigen 1 represents the lower phase obtained from crude lipid extract after Folch partition (LCL). Antigen 2 is a highly purified glycosphingolipid fraction (GSL). The LCL antigen discriminated quite well the reactivities of Chagasic patients' sera and sera from healthy individuals, as well as between the serum from a T. cruzi‐immunized rabbit (TIRS) and normal rabbit serum (NRS). A strong reactivity with GSL was obtained with TIRS. Reactivity with GSL was also obtained with human Chagasic sera. Compared to a group of normal individuals, the reactions of antibodies directed against lipid antigens were considerably increased in sera of patients with Chagas disease. Chagasic sera did not differentiate between glycolipids with terminal β‐glucosyl or β‐galactosyl nonreducing units. They discriminated, however, glucosylceramides with differences in the ceramide structure. To determine the specificity of Chagasic sera, antibodies isolated on LCL‐immunosorbent (LCL‐Ch Abs) as well as on laminin‐immunosorbent (Lam‐Ch Abs) were tested against laminin and LCL antigens. We found that Lam‐Ch Abs reacted with murine laminin, whereas the reaction was negative with LCL. In contrast, the LCL‐Ch Abs reacted either with LCL antigens or with laminin. The reactivity with laminin was strong in comparison with LCL. Results suggest that although the glycolipids are recognized by Chagasic patients' sera, the reactive antibodies are not specific since they reacted quite well with murine laminin. Polyspecific antibodies from Chagasic sera have already been described using other unrelated antigens. © 1994 Wiley‐Liss, Inc.