A–D, Ag-specific Ab responses of wild type (WT), CD21/35−/−, CD19−/−, CD21/35−/−CD19−/− and CD21/35−/−CD19+/− mice following immunization with (A) PPS-3, (B) DNP40-Ficoll, (C) DNP-KLH, or (D) TNP-LPS (CD19−/− and CD21/35−/−CD19−/− mice were omitted). Sera were collected at the indicated timepoints and analyzed by ELISA for PPS-3- (A) DNP- (B, C), or TNP-specific (D) Abs (3–8 mice/genotype). E, Ab responses to TNP52-Ficoll (upper panel) and TNP4-Ficoll (lower panel) in WT, CD21/35−/−, C3−/−, CD21/35−/−C3−/−, and CD21/35−/−CD19−/− mice. Sera were analyzed for TNP-specific Abs 14 d post-immunization by ELISA. Data points for individual mice are shown (n=4–5 mice/group). A–E, Mean Ab (±SEM) levels significantly different than WT mice are indicated by asterisks; *, p<0.05.