FIG. 2.

Bound complement is unaffected by gamma radiation-induced changes in capsule size. Cryptococcal cells with induced capsule were incubated in mouse serum to allow complement deposition on the capsule, which localizes and covalently binds to the inner capsule. Cells were then irradiated for 0, 5, 10, 20, 30, or 40 min, and an immunofluorescence assay was performed to detect complement localization (green fluorescence, FITC). To detect capsule edge, MAb 18B7 was added after the serum incubation and then detected with goat anti-mouse IgG-TRITC. For each time point, upper left panel, light microscopy; upper right panel, rhodamine; lower left panel, FITC; lower right panel, merge of the two fluorescences. Bar, 5 μm.