Characterization of antigens from type A and B yeast cells of Histoplasma capsulatum.

The antigenic composition of cytoplasmic extract and culture filtrate antigens of type A and B yeast cells of Histoplasma capsulatum grown in a synthetic medium was studied. These preparations from type A and B yeast cells contained varying amounts of protein, carbohydrates, and protein-carbohydrate complexes. The antigenic analysis of these preparations was performed by antigen-antiserum absorption with subsequent immunodiffusion and cross-immunoelectrophoresis with absorption in situ in an intermediate gel. All protein antigens observed in culture filtrate of either type A or B yeast cells were also present in the cytoplasmic extracts of the same type. The cytoplasmic extract of type A and B yeast cells each contained certain characteristic antigens that were not shared by the other type. Rocket immunoelectrophoresis with different molecular weight fractions of the antigenic preparations from both types indicated the polydisperse nature of Histoplasma yeast cell antigens.