Isolation of a coccidioidin component that reacts with immunoglobulin M precipitin antibody

Detection of immunoglobulin M (IgM) precipitin antibody to coccidioidin, the autolysate of mycelial-phase cells of Coccidioides immitis, is an important serologic aid in establishing a diagnosis of primary coccidioidomycosis. In the present study, the component of coccidioidin that reacts with IgM precipitin antibody was isolated by a combination of immunoaffinity and anion-exchange chromatography. Antigenic analysis of the purified antigen in two-dimensional immunoelectrophoresis against goat anti-coccidioidin revealed a precipitinogen characterized by a complete cathodal leg and a partial anodal leg. The reactivity of this incomplete precipitating antigen with anti-C. immitis IgM was established by serologic assays and by the adsorption of reference IgM precipitin antibody on solid-phase immunosorbents containing the purified precipitinogen. The isolation of the coccidioidin component that reacts with IgM precipitin antibody and the production of monospecific antibody will provide the necessary reagents for the development of a sensitive immunoassay for detecting this serodiagnostic response.