Histologic Reactions to Cell Walls of an Avirulent and a Virulent Strain of Blastomyces dermatitidis

Mice were inoculated ip with cell walls, and fractions thereof, from two strains of Blastomyces dermatitidis that differed in virulence. Large doses of trypsintreated cell walls of the virulent strain KL-1 were lethal, produced tissue necrosis, and evoked a granulomatous reaction. In contrast, cell walls of the avirulent strain GA-1 were lethal for mice and produced tissue necrosis, but did not elicit a granulomatous response. After extraction of the cell walls with 1 N NaOH, tissue necrosis was observed in mice inoculated with the alkali-insoluble cell walls of either strain, whereas granulomas were produced only in the mice inoculated with the alkali-soluble material of the virulent strain. The inability of the avirulent strain to elicit a granulomatous response is considered to be attributed to chemical differences in its alkali-soluble fraction. Blastomycosis is a disease characterized by a suppurative and granulomatous inflammatory reaction, although the extent of these reactions may vary considerably from one individual to another. Baker reported that mice inoculated ip with large doses of heat-killed, yeast-phase cells of Blastomyces dermatitidis exhibited a histologic reaction similar to that produced in mice by an active in