Comparison of partially purified mycelial and culture filtrate antigens of Aspergillus fumigatus by enzyme-linked immunosorbent assay

An aqueous extract of Aspergillus fumigatus mycelium was fractionated by precipitation with ammonium sulphate to give protein-enriched and carbohydrate-enriched preparations. The antigenic activity of the fractions so obtained was assessed in an enzyme-linked immunosorbent assay using pooled positive and negative reference sera. The best discrimination between such sera was obtained when using either the fraction insoluble in 50--75% ammonium sulphate or the material soluble in a saturate solution of the salt. This system was then used in parallel with commercial A. fumigatus extracts to test sera of patients with and without clinical aspergillosis. The implications of the results are discussed.