Figure 3.

Mechanisms of complement activation studied with fluid phase markers: formulations of SPIO NWs are described in Figure 1 (dextran/Fe ratios abbreviated as 3, 6, and 9 g) were incubated in human sera at 0.2 mg Fe/mL as described in Section “Materials and Methods”. Zymosan (positive control) was at 0.2 mg/mL; (A) generation of soluble terminal membrane attack complex sC5b-9 in a healthy human serum; (B) generation of Bb as a marker of the AP activation in C2-depleted serum [the same serum source as in (A), where C2 was depleted immunochemically] and after addition of recombinant C2 (650 μg/mL) to C2-depleted serum; (C,D) effect of properdin antibody on AP activation and C5a generation, respectively. White bars: no inhibitor, gray bars: control isotype matched antibody, black bars: anti-P antibody. Non-parametric two sided t-test, n = 3 (two different human sera were used, and the results of a typical experiment are presented); *p < 0.05; **p < 0.01. None of the SPIO NWs generated sC5b and Bb in the presence of 10 mM EDTA (not shown).