Class-specific antibodies in young and aged humans against organisms producing superficial fungal infections.

Class-specific antibodies (IgG, IgA and IgM) against Candida albicans, Pityrosporum orbiculare and Trichophyton rubrum were measured in the serum from twenty-one young subjects (aged 23-44) and twenty elderly subjects (aged 70-88) who did not have a history of significant superficial fungal infections. We found that (a) antibody to all three organisms was present in all subjects in both groups, (b) except for a reduced level of IgM antibody against P. orbiculare, the elderly subjects demonstrated humoral responses in these assays similar to those of the young subjects, (c) IgA antibody was present in higher amounts against C. albicans that against P. orbiculare or T. rubrum in both groups, and (d) the proportion of IgM antibody against T. rubrum was higher than that against the other two organisms. These findings suggest that the ecology of these three organisms with respect to the normal human host may be reflected in the serological responses against them.