A partially purified glycoprotein antigen from Aspergillus fumigatus

Culture filtrate antigens of Aspergillus fumigatus were fractionated by isoelectric focusing using a pH gradient of 4-6.5. Three fractions, namely, 18, 19 and 20 were pooled and subjected to immunochemical analysis. It contained a concanavalin A binding glycoprotein. Antibody raised against this component was used to prepare an affinity column of IgG-Sepharose and was used to purify crude culture filtrate antigens. This component produced three precipitin arcs in crossed immunoelectrophoresis using anti-A. fumigatus rabbit serum. This fraction has an isoelectric point of 6.5 and showed three components in two-dimensional electrophoresis with approximate molecular weights of 20, 40 and 80 kilo daltons. This antigen reacted with patient sera in the biotin-avidin linked immunosorbent assay and showed high levels of anti-A. fumigatus IgG and IgE antibodies in allergic bronchopulmonary aspergillosis and IgG antibodies in aspergilloma. Both controls and Aspergillus skin test positive asthmatics showed only low levels of specific antibodies. Because of the purity of this antigen, its potential use as a standardized antigen in the detection of antibody is discussed.