Concerning the specificity of dermatophyte-reacting antibody in human and experimental animal sera

Common antigens were shown in T. rubrum, T. mentagrophytes, Hormodendrum sp., and Penicillium sp. by agar gel diffusion, hemagglutination, and hemagglutination-inhibition tests. The immune response of rabbits to injections of dermatophyte mycelium was shown by the development of a state of hypersensitivity and by antibody production. Antibody in rabbit anti-dermatophyte serum could be completely removed by absorption with dermatophyte mycelium but only partially by mycelium of Penicillium sp., indicating that the sera of animals immunized with dermatophytes contain antibody specific for the dermatophytes as well as antibody directed against a common antigen found in dermatophytes, Hormodendrum sp., and Penicillium sp. Antibody against T. rubrum was found in the sera of 93 adult Negroes and Caucasians tested, irrespective of the presence or absence of clinical ringworm, and in 27 out of 35 Caucasian children without ringworm. Titers among children were lower than among adults. Titers among apparently normal adults did not differ significantly from those with ringworm. Antibody in human serum could be completely removed by absorption with mycelia of Hormodendrum sp., Penicillium sp., or dermatophyte, suggesting formation as a result of previous contact with either dermatophyte or saprophyte.