Effect of anti-C5 and anti-C5a on granulocyte responses.N meningitidis H44/76-induced CR3 (CD11b/CD18) expression, phagocytosis of FITC-labeled meningococci, and oxidative burst by N meningitidis were measured in whole human blood after a 10-minute incubation with 2 × 108 meningococci/mL in the presence or absence of the mAbs anti-C5 (clone 137-76, preventing C5 cleavage), anti-C5a (clone 137-26), and an isotype control (6.25-50 μg/mL). Anti-C5 and anti-C5a markedly, and to the same extent, inhibited N meningitidis-induced granulocyte CR3 up-regulation, phagocytosis, and oxidative burst. B indicates baseline (unstimulated sample) at time of incubation (t = 0) or after 10 minutes of incubation at 37°C (t = 10). Results from 1 of 3 representative experiments are shown.
