Antigenic identity of biologically active antigens in coccidioidin and spherulin.

We recently reported the isolation of three clinically relevant antigens from coccidioidin; viz., the antigen that is reactive in the immunodiffusion (ID) assay for detecting tube precipitin (TP) antibody (designated IDTP); the antigen that is reactive in the ID assay for detecting complement-fixing antibody (designated IDCF); and the heat-stable (HS) antigen which, when demonstrated in soluble extracts of fungal cultures by using the IDHS assay, establishes the mycologic identification of Coccidioides immitis. This investigation was undertaken to determine whether the IDTP, IDCF, and IDHS antigens isolated from coccidioidin are of antigenic identity with components in spherulin. By employing the purified coccidioidin antigens in line-immunoelectrophoresis with spherulin and by assaying coccidioidin and spherulin by tandem two-dimensional immunoelectrophoresis against antisera produced to the purified antigens, we report that these three coccidioidin-derived antigens are antigenically identical to precipitinogens in spherulin.