Effect of anti-FH.07 Fab′ fragment on binding of FH to C3 fragments. Binding of FH in the absence or presence of anti-FH.07 to C3b (A), iC3b (B), and C3d (C). C3b (2,045 RU), iC3b (2,039 RU) and C3d (2,055 RU) were amine-coupled to a CM5 chip to assess binding of FH (black lines) or FH in the presence of 4 µM anti-FH.07 Fab′ fragments (FH:07, orange lines). Double injections of a twofold diluting concentration range starting at 2 µM FH were probed in random order throughout. For ease of interpretation, only the sensograms of 2, 1, and 0.5 µM FH and FH:07 are shown. Sensograms were normalized for the molecular weight of FH (155 kDa) or the FH:anti-FH.07 Fab′ fragment complex (205 kDa), respectively. All graphs shown are representative of multiple experiments (n ≥ 2).