Studies on the Antigenic Activities of Yeasts

VI. Analysis of the Antigenic Determinants of the Mannan of Candida albicans Serotype B-792

Abstract

In order to provide further information about the immunochemical differences between two mannans of Candida albicans serotype A and serotype B, quantitative precipitation-inhibition tests of anti-C. albicans serotype B serum were carried out in the present study. Oligosaccharides were prepared by acetolysis of a homologous mannan, and α1→2 linked di-, tri-, tetra-, penta- and hexasaccharide were separated in chromatographically homogeneous states. The latter two oligomers contained a small amount of an isomer containing α1→2 and α1→3 linkages. In the precipitation-inhibition tests of anti-C. albicans serotype B serum with its homologous mannan and heterologous mannan of C. albicans serotype A, the inhibitory power of the oligomers was of the following order; hexa->penta->tetra->tri->disaccharide, and the amounts for 50%-inhibition of the former 4 oligomers were 0.02-0.03, 0.050.07, 0.1-0.2 and 0.3-0.4 μmoles respectively, whereas disaccharide was very poor inhibitor. The lower oligomers, α1→2 linked tri- and tetrasaccharide, showed considerably strong inhibitory activities. The results obtained in the present study confirmed that the antigenic determinants of the mannan of C. albicans serotype B is the hexasaccharide moiety corresponding to the longest branched chains of mannan, and moreover, the α1→2 linked tri- and tetrasaccharide moieties play an important factor in dominating immunochemical specificity.