Trichophytin extraction: biological comparison of trichophytin extracted from Trichophyton mentagrophytes grown in a complex medium and a defined medium.

The extraction of antigens (trichophytin) from Trichophyton mentagrophytes var. asteroides grown in both a complex medium and a defined medium proved to be reproducible and feasible. These extracts were first evaluated by skin testing in both infected and noninfected guinea pigs. Further evaluation and standardization was accomplished in selected humans by comparing these antigens to a trichophytin known to elicit allergic reactions to the dermatophytes. The trichophytins produced by this extraction procedure gave no false positive (or negative) skin test reactions. These antigens did, however, reliably elicit allergic sensitivity of both the immediate and delayed type. The potency of both complex and defined media antigen was shown to be equal to that of the standard trichophytin.