Aspergillus fumigatus antigens used in the serodiagnosis of aspergillosis.

The diagnostic antigens in Aspergillus serology are mycelial or culture filtrate concentrates. Recent work has been directed towards the separation of defined, reproducible products of greater sensitivity and specificity than crude extracts. Conventional methods of separation have been used; they include fractional precipitation, detergent extraction, chromatography, and preparative isoelectric focusing. Selective staining of the separated fractions has shown many of the more reactive components to be glycoproteins. Affinity binding to Concanavalin A has demonstrated the presence in these of alpha-D-glucopyranose, alpha-D-mannopyranose and/or terminal alpha-D-N-acetylglucosamine. Major amino acid constituents are serine and threonine, together with glutamic and aspartic acids. The more reactive and specific components, as judged by their antibody binding capacity, have molecular weights greater than 70,000; in some cases they are as high as 150,000 to 180,000. Isoelectric focusing gave products with acidic pI values which specifically bound the IgG present in sera from aspergillosis patients. Results from a number of laboratories suggest that a group of acidic glycoproteins constitute the most promising source of a diagnostic reagent for aspergillosis. However, further analysis and a comparison of these substances in an international collaborative study is needed before agreement can be reached on a "standard" antigen preparation.