CHEMILUMINESCENT IMMUNOASSAYS - DISCRIMINATION BETWEEN THE REACTIVITIES OF NATURAL AND HUMAN PATIENT ANTIBODIES WITH ANTIGENS FROM EUKARYOTIC PATHOGENS, TRYPANOSOMA-CRUZI AND PARACOCCIDIOIDES-BRASILIENSIS

Quantitative chemiluminescent enzyme-linked immunosorbent assay (ELISA ) and dot-blotting procedures were developed to evaluate the reactivit y of human antibodies with crude antigens and purified molecules of pa rasites and fungi, mainly Trypanosoma cruzi and Paracoccidioides brasi liensis. Reproducible, highly sensitive, and strictly dose-responding results were obtained, with the specificity depending on the kind of a ntigen used. Mixed antigens (epimastigote membrane and HIV-I heptapept ide) applied in dots could be independently recognized by specific ser a. Purified antigens (T. cruzi F2/3 and P. brasiliensis gp43) at very small concentrations gave specific reactions with patients' sera dilut ed greater than or equal to 1:1,000 and were very poorly reactive or u nreactive with natural antibodies using the chemiluminescent immunoass ays. P. brasiliensis crude antigen Fava Netto polysaccharide antigen ( FNPA) contained peptide epitopes recognized by natural antibodies and carbohydrate epitopes reactive with sera from histoplasmosis patients. It is very important that sensitive chemiluminescence immunoassays be used with purified antigenic molecules to ensure specificity for the diagnosis and follow-up of parasitic and fungal infections. (C) 1994 W iley-Liss, Inc.