Reactivity of Cryptococcus neoformans & Candida species with concanavalin A & blood grouping sera

Forty strains of Cryptococcus neoformans, 30 of Candida albicans, 24 of C. parapsilosis and 10 strains each of C. tropicalis and C. (Torulopsis) glabrata were examined. A 0.2 per cent solution of concanavalin A (Con A) in phosphate buffered saline and commercial anti-A and anti-B blood grouping sera were used in the whole cell slide agglutination test. All the isolates of Candida species strongly reacted with Con A and over 90 per cent were agglutinated by anti-A and -B blood grouping sera. In contrast, except for one strain, Cryptococcus neoformans did not agglutinate with Con A or blood grouping sera. These findings suggest, on one hand, a fundamental difference in the sugar mosaic of the cell surface components of Cryptococcus neoformans and Candida species, and on the other, presence of similar antigenic determinant(s)/receptors on the cell surface of Candida species and human erythrocytes.