In vivo and in vitro cell-mediated immune responses to a cell wall antigen of Blastomyces dermatitidis.

An alkali-soluble, water-soluble cell wall fraction of Blastomyces dermatitidis, designated B-ASWS, was evaluated as an antigen for detecting in vivo (skin tests) and in vitro migration inhibition factor (MIF) production and lymphocyte transformation (LT) responses in Blastomyces-infected guinea pigs. The biological activity of B-ASWS was compared with that of blastomycin KCB-26. The superiority of B-ASWS, in terms of its sensitivity and specificity, was evident in in vivo and in vitro assays. Skin tests responses were obtained in 21 of the 24 Blastomyces-infected guinea pigs, whereas only one of the 14 Histoplasma-infected guinea pigs were significantly greater than those obtained using cell populations from Histoplasma-infected or noninfected guinea pigs. The con-MIF and LT in peritoneal exudate cells and lymph node cells of homologuosly infected animals. In each biological system, the response of the Blastomyces-infected guinea pigs were significantly greater than those obtained using cell populations from Histoplasma-infected or non-infected guinea pigs. The contrasting efficacy of B-ASWS as compared with blastomycin KCB-26, suggests that the cell wall antigen will be a useful tool for detecting cell-mediated immune responses in blastomycosis.