Immunodiffusion studies on the antigens of Histoplasma capsulatum: comparison of mycelial histoplasmin with the yeast phase reagent Histolyn-CYL.

Immunodiffusion assays were performed to determine if H and M antigens associated with mycelial histoplasmin were present in the yeast phase reagent, Histolyn-CYL (H-CYL). Neither H nor M antigens could be detected in H-CYL. However, when H-CYL was reacted against human histoplasmal sera a positive reaction was evidenced in all instances in which a response was elicited with a reference mycelial immunodiffusion reagent.