Humoral autoimmune response to ribosomal P proteins in chronic Chagas heart disease

The C terminal region of a Trypanosoma cruzi ribosomal P protein, encoded by the lambda gt11 JL5 recombinant, defined a major antigenic determinant in chronic Chagas heart disease. Immunopurified anti-JL5 antibodies were tested for anti-human ribosome reactivity by immunoblotting. They recognized the parasite ribosomal P proteins and clearly reacted with the corresponding human P proteins. The peptide R-13, that comprises the 13 C terminal residues of the JL5 recombinant and defines the specificity shared between chronic Chagas heart disease anti-JL5 antibodies and the systemic lupus erythematosus (SLE) anti-P antibodies, was used to study the specificity and the IgG subclass distribution of the anti-R-13 response by ELISA. The R-13 autoepitope is recognized mainly by sera from chagasic patients, but not by sera from malaria patients. Moreover, there was a significant correlation between anti-R-13 antibody levels and anti-T. cruzi antibody titres. The anti-R-13 response was mainly restricted to the IgG1 heavy chain isotype and correlated with the anti-T. cruzi isotype distribution.