Antigenemia in primary coccidioidomycosis

Clinical findings in patients with primary infection due to Coccidioides immitis have suggested that fungal antigenemia may occur. To study this possibility, we devised an inhibition enzyme-linked immunosorbent assay (ELISA) to measure antigenic activity compared to the activity of antigens derived from spherules. Twenty-one of 27 sera from 19 infected patients showed antigenic activity above that found in sera from uninfected persons. Activity was highest early in the course of illness. In other studies, anti-spherulin antibody activity was measured by ELISA, which demonstrated an association of antigen activity with IgM, but not IgG or IgA. One possible explanation for this phenomenon is that IgM antibody and antigen are present as circulating immune complexes.