CHEMICAL AND IMMUNOLOGICAL ANALYSIS OF THE ASPERGILLUS-FUMIGATUS CELL-WALL

Hyphal-wall preparations of Aspergillus fumigatus have been analysed b y sequential treatment with KOH, nitrous acid and again with KOH. By a cidification of the alkali-soluble extract, a polyglucose was precipit ated which showed an X-ray diffraction pattern similar to that of (1 - -> 3)-alpha-glucan. The remainder of the alkali-soluble fraction was p recipitated with ethanol; it contained all the mannose, galactose and protein of the wall and, in addition, 6.2% of the amino sugars. This w all-associated glycoprotein, following SDS-PAGE and immunoblotting, re acted with antisera raised against several mycelial extracts of A. fum igatus. Sera from patients with aspergilloma have antibodies which rec ognize components of this glycoprotein. The glycoprotein nature of the se antigens was shown by their ability to bind Lens culinaris lectin. In addition, the antigen/antibody binding could be disrupted by exposu re of antigen to periodate oxidation, hydrolysis with dilute acid or p retreatment with a large excess of an exo-beta-D-galactofuranosidase. The alkali-insoluble fraction consisted of a covalently linked glucan- chitin complex. Nitrous acid treatment, which specifically disrupts gl ycosidic linkages involving glucosamine, did not solubilize much mater ial but changed the X-ray diffraction pattern from diffuse to a patter n showing the characteristic lines of crystalline (1 --> 3)-beta-gluca n and chitin. Most of the glucan became alkali-soluble after this trea tment, and the insoluble residue appeared to contain crystalline chiti n.