Neonatal WT, C4–/–, and Fb–/– mice were injected i.d. with a suboptimal dose of pathogenic rabbit anti-mBP180 R530 IgG (2.0 mg/g body weight). The animals were examined at 12, 24, 48 hours, and up to 14 days after IgG injection. (A) Clinical score. The IgG-injected mice were examined at 12, 24, and 48 hours after injection (n = 12 per group). Disease severity is expressed as mean clinical disease score ± SEM. Three independent experiments were performed per group. (B) ELISA. Levels of circulating anti-mBP180 IgG were quantified and expressed as relative OD readings. There were no significant differences between WT and Fb–/– mice at all time points. n = 6 per group. (C) MPO activity assay. PMN infiltration in WT and Fb–/– mice (n = 6 per group) was significantly different on day 1 (P = 0.04), but not on day 3 (P = 0.34), day 7 (P = 0.15), or day 14 (P = 0.74). *P < 0.05, ΧP < 0.001 versus WT at the respective time points.