FIG. 1.

(A) Percent phagocytosis for 8 different C. neoformans strains from A. castellanii. After incubation at a 1:1 ratio, 96-well plates were washed, cells were stained, and a minimum of 200 cells/well were counted to determine the percent phagocytosis. This value is defined as the number of A. castellanii with internalized yeast per total number of A. castellanii cells counted shown as a percentage. (Inset) Linear regression of capsule volume (μm³) versus percent phagocytosis (R² = 0.01518). (B) Phagocytosis assays after capsule induction. A. castellanii cells were allowed to phagocytose various strains of C. neoformans before and after the strains had been placed in media to increase the size of the polysaccharide capsule. All strains showed a decrease in the phagocytic index after the capsules had enlarged. (Inset) Comparison of percent phagocytosis before and after capsular enlargement (P < 0.05). The experiments shown in panels A and B were done at different times, and the differences in the values of phagocytosis measured for individual strains are within the experimental error of this assay. (C) Phagocytosis assay with acapsular mutants and capsule complemented strain. A. castellanii phagocytosis assays were performed with the wild type, CAP59 mutant (an acapsular mutant, C536), and complemented strains of C. neoformans (C538).