Fig. 7.

Physiological importance of 2H1-mediated capsule damage. (A) The effects of complement deposition on the capsule of heat killed H99 C. neoformans was examined after incubation with 2H1 mAb or no Ab for 7 d. Cells were stained with specific fluorophore conjugated secondary Abs to visualize mAb and complement localization. (Scale bar, 6 µm.) (B) Phagocytic opsonization was measured for untreated H99 C. neoformans cells, cells treated with 2H1 mAb (with or without subsequent Ab removal) and guinea pig complement (with or without 2H1 treatment and removal). Statistically significant differences in phagocytic index where observed between untreated cells and all treatment conditions (χ² test for differences). The addition of complement to H99 C. neoformans cells treated with 2H1 yields a highly significant increase in phagocytic index compared to cells only treated with 2H1, suggested that altered complement deposition as a result of catalytic mAb remodeling of the capsule diminishes the antiphagocytic properties of the capsule (*P < 0.5; **P < 0.01; ***P < 0.001).