Comparative studies on the detection of delayed dermal hypersensitivity in experimental animals with lysate and filtrate antigens of Blastomyces dermatitidis.

Yeast cell and mycelial lysate and filtrate antigens prepared in our laboratory from two strains of Blastomyces dermatitidis (canine isolate T-58 and human isolate Le) were evaluated with respect to the detection of delayed dermal hypersensitivity in hairless guinea pigs previously immunized with killed whole yeast cells from two strains of Blastomyces dermatitidis (T-58 and Le) and Histoplasma capsulatum (strain G-217A). The optimal potential reactivity (reactivity minus cross-reactivity) with regard to eliciting a dermal response in animals sensitized with B. dermatitidis was achieved with the yeast phase lysate and filtrate antigens prepared from both T-58 and Le isolates (mean axes of induration values ranging from 14.0 to 15.9 mm). In contrast, the mycelial phase reagents exhibited lower potential reactivity (mean axes of induration values ranging from 5.3 to 10.5 mm).