Increased NP-specific Ig secretion in SWAP-70^−/− mice. SWAP-70^+/+ and SWAP-70^−/− mice were immunized with NP-KLH emulsified in CFA. (A-D) Serum response to NP-KLH immunization of wt and SWAP-70^−/− mice. At the indicated times, samples were collected and total NP-specific anti-IgM (A), IgG1 (B), IgG2a (C), and IgG2b (D) Ab titers were determined by ELISA with NP₁₂-BSA as capture antigen. Black and white circles represent individual mouse for wt and SWAP-70^−/−, respectively. Black and gray bars represent the mean average for wt and SWAP-70^−/−, respectively. Values are expressed as arbitrary optical-density units at 405 nm. The optical-density values for CFA-injected mice are less than 0.001. Right panels represent the mean ratios of high-affinity anti-NP₃ versus total anti-NP₁₂ serum Abs. Data are from 5 independent experiments. ELISPOT analysis of total (E) and high-affinity (F) IgG1 secretion by splenocytes from wt and SWAP-70^−/− mice at the indicated times after NP-KLH immunization. Data represent the mean number of spots. (G) Flow cytometry of GL7 and IgG1 expression in NP⁺B220⁺ cells in spleen at the indicated times. (H) Spleen stained for PNA (red) and IgG1 (green) 6 days after immunization. All scale bars represent 200 μm.