Grouping of Aspergillus species with exoantigens.

Ninety-two slant extracts prepared from 2-week-old cultures of seven Aspergillus groups, nonsporulating "albino-type" A.fumigatus, Blastomyces dermatitidis, Histoplasma capsulatum, 3 Penicillium spp., 2 Pseudallescheria spp., 3 Paecilomyces spp., and Acremonium sp., were analyzed concurrently against antisera to A. fumigatus, A. flavus, A. nidulans, A. niger, and A. terreus. The extract of each of the aforementioned five pathogenic Aspergillus spp. produced 2-11 specific antigen-antibody complexes after reacting with its homologous antiserum. Antisera prepared against extracts to these pathogenic aspergilli demonstrated variable intra-generic crossreactivity, which were eliminated by adsorption with heterologous Aspergillus spp. antigens. Fewer nonspecific reactions were noted with the reference antigen-antibody precipitates of A. nidulans and A. Terreus than with reference precipitates of the other Aspergillus spp. Exoantigen extracts of "albino-type" isolates of A. fumigatus produced two to five specific precipitins against anti-A. fumigatus serum only. Based on the specific reactions produced by the eight albino-type isolates and 1 Aspergillus sp. isolate, all these fungi were identified correctly and placed in the A. fumigatus group. Analyses of conventionally identified A. fumigatus, A. flavus, A. nidulans, A. niger, and A. terreus including an isolate of A. parasiticus, enabled us correctly to classify them (51/51, or 100%) into their respective groups. Specific Aspergillus spp. antigen-antibody precipitates were characterized and used as references in exoantigen tests. None of the fungi in the genera other than Aspergillus produced antigens identical to the selected reference antigens.