Anti-FH.07 protects E_Sfrom induced complement-mediated hemolysis. (A) E_S hemolysis was induced in 10% (vol/vol) NHS by inhibiting FH with anti-FH.09 (n = 3). Hemolysis was measured at 412 nm and corrected for background at 690 nm. The hemolysis observed by incubation of E_S with 0.6% (wt/vol) saponin was set to 100%. (B) Titration of anti-FH.07 in the induced E_S hemolysis assay (n = 3). For this E_S hemolytic assay, 0.067 µM (10 µg/mL) anti-FH.09 was used, resulting in 87% E_S lysis as indicated with the dashed lines in panel A. (C) Comparison of the inhibitory effect of anti-FH.07 and eculizumab in the E_S hemolytic assay performed in panel B (after normalization). Dashed line indicates 50% of the normalized E_S hemolysis. (D) IC₅₀ values of anti-FH.07 and eculizumab in the induced E_S hemolytic assay as in panel C (n = 3) using either a NHS pool or a pool of sera from 4 healthy donors lacking the CFHR1 gene (CFHR1^−/− pool). (E) Incubation of E_R with 10% (vol/vol) NHS serum in the presence of eculizumab or anti-FH.07 at the indicated concentrations (n = 2). All data are presented as mean with standard deviation. *P < .05, ****P < .0001, 2-way ANOVA.