Antigenic relationship between downy and granular forms of Trichophyton mentagrophytes and Trichophyton rubrum.

One strain each of granular and downy varieties of Trichophyton mentagrophytes and two strains each of granular and floccose colonial types Trichophyton rubrum were used for preparation of antigens. The antigens were analyzed by double diffusion against homologous and heterologous antisera raised in rabbits. A total of 17 distinct antigens were recognized, seven of which were common to two dermatophytes. Granular and downy varieties of the Trichophyton species produced on additional line of nonidentity. Cross reactions failed to establish any relationship between similar morphologic forms of different dermatophytes. One isolate of T. rubrum, which was originally the floccose culture type but changed into the granular form after artificial infection, showed an antigenic relationship to the floccose culture.