Activation of peritoneal macrophages by concanavalin A or Mycobacterium bovis BCG for fungicidal activity against Blastomyces dermatitidis and effect of specific antibody and complement.

With a new short-term assay, where the reduction of CFUs in the inoculum could be measured, we investigated the killing of the dimorphic fungal pathogen Blastomyces dermatitidis in its yeast phase by murine peritoneal macrophages. Peritoneal macrophages from concanavalin A- or Mycobacterium bovis BCG-treated mice, but not resident or thioglycolate-elicited macrophages, significantly reduced the CFUs of B. dermatitidis in the inoculum. The activation of peritoneal macrophages for fungicidal activity by concanavalin A treatment was shown to be dose dependent and transient, i.e., absent after 72 h. These results indicate that it is possible for murine peritoneal macrophages to kill B. dermatitidis in vitro. The addition of specific antibody or complement or both did not enhance the killing of B. dermatitidis by these nonspecifically activated macrophages.