Factors influencing the production of H and M antigens by Histoplasma capsulatum: development and evaluation of a shake culture.

Studies were undertaken to improve the production of histoplasmin for use in complement-fixation tests and in the determination of H and M antibodies. A shake culture method performed at 25 C was developed with a yeast-phase inoculum. Eight strains of Histoplasma were tested in three synthetic media to evaluate the effects of strain and medium on H and M antigen production. Intrastrain variation was negligible, and antigen production was reproducible. All of the strains produced H antigen; six strains produced both H and M antigens, and two produced only H antigen. The time of H and M antigen appearance varied with the medium; M antigen appearance was dependent upon the strain and medium used. Titers of M antigen appeared to be greater in stagnant culture.