Attachment of Blastomyces dermatitidis conidia to murine bronchoalveolar macrophages: characterization of binding and elicitation of respiratory burst.

We studied the mechanisms of adherence of Blastomyces dermatitidis conidia to murine bronchoalveolar macrophages and the ability of the conidia to elicit an increase in macrophage O2- production, using an avirulent fungal strain. The number of cell associated conidia was counted by visual inspection of 2 hour macrophage monolayers incubated with conidia and O2- was measured by reduction of ferricytochrome c. Adherence of conidia to bronchoalveolar macrophages was time dependent and reached a plateau after 30 min (36 +/- 5%, 51 +/- 22%, and 36 +/- 17% macrophages with adherent conidia after 15, 30, and 60 min, respectively). Both Ca+2 and Mg+2 were required. The carbohydrates mannose, mannan, fucose, alphamethylmannoside, beta-glucan, galactose, N-acetylglucosamine and chitotriose (100-1000 micrograms/ml) did not inhibit adherence of conidia to macrophages. Trypsin treatment of macrophages or conidia did not affect binding. Conidia did not stimulate bronchoalveolar macrophage production of O2- above baseline concentrations (2.0 +/- 0.9 vs 0.8 +/- 0.5 nmol O2-, p greater than 0.05). We conclude that murine bronchoalveolar macrophage--B. dermatitidis conidia interactions occur primarily by a non-lectin-like attachment and do not result in the production of macrophage derived O2-.