GC formation in LN. (A) SWAP-70^+/+ and SWAP-70^−/− mice were immunized with SRBCs or PBS as control. Six days after immunization, mesenteric LN were stained for PNA (green) and B220 (red). (B) SWAP-70^+/+ and SWAP-70^−/− mice were immunized with CFA or CFA-KLH in the footpad. Six days after immunization, draining popliteal LN were stained for PNA (green) and B220 (red). Scale bars represent 200 μm.