GC formation defect is intrinsic to SWAP-70^−/− B cells. SWAP-70^+/+ or SWAP-70^−/− total splenocytes (A-D) or purified B cells (E) were adoptively transferred into μMT B cell–deficient mice, and 1 day after, mice were immunized with SRBCs or injected with PBS as control. (A) Spleen sections of SRBC-immunized μMT transferred with total splenocytes were stained for GC using PNA (green), B220 (red), and CD3 (blue) 6 days after immunization. (B) Percentage of B follicles containing GC in spleen sections of immunized animals at the indicated time. (C) Flow cytometry of GC B cells defining as CD19⁺ B cells that are positive for PNA. Numbers indicate percentage of cells. (D) Percentage of PNA⁺ cells among B cells. (E) Spleen sections of control or SRBC-immunized μMT transferred with purified B cells were stained for GC. Scale bars represent 200 μm.