Two-dimensional immunoelectrophoresis of histoplasmin and a purified polysaccharide-protein antigen of Histoplasma capsulatum.

Crude histoplasmin and a polysaccharide-protein complex (PPC-histo) antigens obtained from culture filtrates of Histoplasma capsulatum were analyzed by single and tandem two-dimensional immunoelectrophoresis (TD-IEP) using a rabbit hyperimmune anti-histoplasmin polyvalent serum. Single TD-IEP showed 14 arc precipitates for histoplasmin. Continuity of arcs 2, 6, and 7, and 9 and 10 was observed, suggesting a different polymeric configuration of the same antigen. This was also confirmed in tandem TD-IEP of histoplasmin with homologous (PPC-histo) and heterologous PPC's from Blastomyces dermatitidis, Paracoccidioides brasiliensis and Coccidioides immitis. Tandem TD-IEP of histoplasmin and PPC-histo displayed a similar antigenic pattern to histoplasmin alone, being arcs 1 and 3 more evident and apparently present only in histoplasmin and PPC-histo. Tandem TD-IEP showed common antigens among the other heterologous fungal purified antigens, and seems useful to observe the multiplicity of antigens present in fungal preparations and to identify those precipitates (arcs 1 and 3) that are predominant in the purified preparation.