Fig. 5.

Accelerated GC reaction of Pkn1^−/− mice is B-cell intrinsic. Eleven-week-old WT and Pkn1^−/− mice were immunized with NP-CGG/CFA. (A) Flow cytometric analysis of GC B cells (B220⁺PNA^hiCD95⁺) was performed 7 d after immunization. (B) Statistical analyses were performed using four to five mice. **P < 0.01, based on Student’s t test. (C and D) Naïve Pkn1^+/+ B cells expressing GFP along with equal numbers of Pkn1^−/− B cells were transferred into B-cell–deficient (μMT) mice, after which the mice were immunized with KLH/CFA. Splenocytes and mesenteric lymph node cells were prepared from recipient mice on either day 7 or day 21, and the number of B cells was determined. (C) Schematic representation of the transfer experiment. (D) Fraction of total (CD19⁺) and GC (CD19⁺PNA^hiGL7⁺) B cells from transferred WT (open columns) and Pkn1^−/− (closed columns) cells in the spleen and mesenteric lymph nodes. Day 7 mice were unimmunized control mice that were examined 7 d after the cell transfer (day 7 nonimmunized). Representative data are shown for at least four mice per group.