FIG. 5.

Effect of exogenous antimannan IgG on formation of alternative pathway initiation sites. Yeast cells were incubated in a complement binding medium that contained 40% mannan-absorbed NHS and 26 μg of antimannan IgG per ml of reaction mixture (classical pathway intact), 40% mannan-absorbed and EGTA-chelated NHS (antibody-independent activation of the alternative pathway), or 40% mannan-absorbed and EGTA-chelated NHS and 26 μg antimannan IgG per ml reaction mixture (antibody-dependent activation of the alternative pathway). Yeast cells were stained with FITC-labeled goat anti-human C3 antibodies.