Factors affecting the antigenicity of Trichophyton rubrum

Nitrogen determinations, performed upon the mycelia of Trichophyton rubrum, indicated that both the total nitrogen to mycelial weight ratio and the protein nitrogen to mycelial weight ratio decreased as the age of the mycelia increased. An increase in nitrogen concentration in the medium produced an increase in the total nitrogen to mycelia weight ratio, but did not necessarily increase the protein nitrogen to mycelial weight ratio. The optimal nitrogen source concentration which produced the highest protein nitrogen to mycelium ratio was found to be considerably less than that recommended in most standard Sabouraud medium formulations. Antisera to antigen preparations, grown on low concentrations of Multipeptone, produced more lines in the gel diffusion reaction than did antisera to antigens grown on standard concentrations of Multipeptone. Antisera to antigenic preparations from 2-week-old mycelia exhibited better and sometimes more lines than those of antigens prepared from 1- or 3-week-old mycelia, regardless of the nitrogen concentration in the medium. Dialysis and storage of the antigen produced no change in the quality of the precipitin lines, even though both processes involved considerable loss of Lowry protein. Immunofluorescence studies showed that young mycelia were more antigenic than the old mycelia, since a substantial degree of cell wall fluorescence was exhibited by the young mycelia, especially at the hyphal tips. Older mycelia lacked this fluorescence. An extracellular antigen was also found to be associated with the young mycelia, but cytoplasmic fluorescence was not observed.