Immunochemical studies on the galactomannans isolated from mycelia and culture broths of three Hormodendrum strains.

Six major antigenic galactomannans isolated from both mycelia and culture broths of three representative strains of three species of the genus Hormodendrum, H. pedrosoi IFO 6071, H. compactum IFO 6726, and H. dermatitidis IFO 6421, were investigated for their immunochemical properties by precipitin reaction and the passive cutaneous anaphylaxis test. We found that partial acid hydrolysis of the these galactomannans with 0.005 M sulfuric acid yielded free galactose and corresponding acid-resistant core moieties. In agar-gel double-diffusion reactions, no acid-resistant core moiety of galactomannan showed a corresponding precipitin line against homologous antiserum, indicating that the acid-labile galactofuranosyl residues were solely responsible for the precipitin activity of these galactomannans. All galactomannans and their core moieties gave sharp cross-precipitin lines against anti-Saccharomyces cerevisiae serum, specific for the alpha1 leads to 3- or alpha1 leads to 2-linked D-mannopyranosyl residue. Quantitative precipitin reactions of the same antigen-antibody systems showed that all acid-resistant core moieties were completely inactive in the homologous systems but were highly cross-reactive with anti-S. cerevisiae serum. Passive cutaneous anaphylaxis tests using guinea pigs sensitized with homologous antisera or with anti-S. cerevisiae serum provided results consistent with those obtained in the in vitro assay.