FIG. 2.

Influence of Fc-free antimannan Fab M1 on the initiation of C3b deposition to C. albicans yeast cells. (Top) Kinetics of C3b deposition in the presence of 10 μg M1 per ml from 2 to 8 min in yeast-absorbed NHS was determined when both the classical and alternative pathways were active (○, without EGTA) or when only the alternative pathway was active (●, with EGTA). Yeast-bound C3 was quantified with FITC-anti-C3 antibody and flow cytometry. (Bottom) Dose effect of M1 on the pattern of C3 deposition through the alternative pathway. Yeast cells were incubated for 4 min in yeast-absorbed NHS containing 2.5, 10, or 40 μg M1/ml in the presence of EGTA. Yeast-bound C3 molecules were detected with FITC-anti-C3 antibody and visualized with fluorescence microscopy. The pattern of M1 binding to yeast cells was visualized with FITC-anti-human κ antibody and fluorescence microscopy and is shown as a comparison (Bottom, far right). A representative experiment from three is shown.