Figure 2.

The hC3Nb2 inhibits classical pathway-mediated hemolysis. The classical pathway was activated on sheep erythrocytes by anti-sheep erythrocyte antibodies. The activated sheep erythrocytes were incubated in 7.5% NHS (A) or FB-depleted serum (B). The effects of hC3Nb2 (black) were compared with those of the alternative pathway inhibitor hC3Nb1 (light gray) and its inactive hC3Nb1 (W102A) mutant (dark gray). Lysis, as measured as absorption at 405 nm in the supernatants, was normalized to lysis by H₂O (100%), whereas erythrocytes incubated in PBS were defined as 0% lysis. Dashed lines, putative C3 concentration in 7.5% serum. Average and S.D. (error bars) are shown for n = 3 experiments in A and n = 2 experiments in B.