PURIFICATION AND CHARACTERIZATION OF THE SEROTYPE-SPECIFIC POLYSACCHARIDE ANTIGEN OF TRICHOSPORON-CUTANEUM SEROTYPE-II - A DISEASE-RELATED ANTIGEN OF JAPANESE SUMMER-TYPE HYPERSENSITIVITY PNEUMONITIS

Summer-type hypersensitivity pneumonitis (SHP) is a unique type of hyp ersensitivity pneumonitis and the most prevalent in Japan. Our previou s study clarified that the causative agent of the disease is Trichospo ron cutaneum, and that the patients with SHP have high titres of antib odies against the serotype-specific antigen of polysaccharide nature w hich exist in the high molecular weight fraction of the culture supern atant of the yeast. In this study, we purified the serotype-specific a ntigen of serotype II T. cutaneum by gel filtration and affinity chrom atography using a monoclonal antibody, D-8, specific for a high molecu lar weight antigen of serotype II T. cutaneum, and elucidated the stru cture of the antigen. This affinity-purified antigen was shown to be a n essentially acidic polysaccharide comprising mannose, xylose, and gl ucuronic acid (6:44:4.7). Chemical analysis showed that this polysacch aride antigen contains a (1-3)linked mannan backbone attached with sho rt side chains of(1-4)-linked mannose and a small proportion of(1-2)-l inked xylose residues by substituting the 2- or dr-positions of the (1 -3)-linked mannose residues of the main chain. Approximately one-fifth of the side chains were terminated with glucuronic acid residues. The antigenic epitope of the serotype-specific antigen was shown to invol ve the terminal glucoronic acid residues as revealed by immunodiffusio n test and sandwich enzyme-linked immunosorbent assay using monoclonal antibody D-8.