Studies on the Antigenic Activities of Yeasts

IV. Analysis of the Antigenic Determinant Groups of the Mannan of Candida albicans Serotype A

Abstract

In order to identify the antigenic determinant groups of the mannan of C. albicans serotype A, six kinds of manno-oligosaccharides of up to 7 units in chain-length connected by α1→2 linkages were prepared from the partial acetolysate of the parent mannan. In the precipitation-inhibition test of anti-C. albicans serotype A serum with its homologous mannan, inhibitory power of the oligosaccharides was of the followingorder:heptaose_??_hexaose>pentaose>tetraose>triose>biose, and the amounts for 50%-inhibition of the former four oligosaccharides were 0.08, 0.10, 0.50 and 3.0 μmole respectively, and the inhibitory power of the latter two oligomers at 0.5 μmole were 8 and 5% respectively. On the other hand, the cross-inhibition test of anti-C. albicans serotype A serum with the heterologous mannan of C. albicans serotype B afforded the result that the order of inhibitory activities was hexaose>heptaose>pentaose>tetraose>triose>biose, and that the amounts for 50%-inhibition were 0.05, 0.08, 0.1, 0.45, 0.50 and 3.0 μmole respectively. Furthermore, the results of inhibition test on the anti-C. albicans serotype A serum absorbed with the mannan of C. albicans serotype B revealed that the biose, triose and tetraose did not show significant inhibitory power in the range employed, whereas the pentaose, hexaose and heptaose did not significantly affect the inhibitory. activities. Thus, it was concluded that the antigenic determinants of the mannan of C. albicans serotype A are α1→2 linked hexaose or heptaose moieties. Based on the above facts, the serological differences between two antigenic mannans of C. albicans serotype A and B may reside at least in the length of the antigenic determinants in which the former is longer than the latter considering the length of the α-D-mannopyranosyl residue.