B cells in WASp-deficient mice exhibit a higher turnover rate. (A-C) WT and WASp^−/− mice were continuously fed BrdU via the drinking water for up to 7 days. Mice were killed on day 3 or 7 and splenocytes stained for BrdU in addition to surface makers to identify B-cell subsets. Percentage of BrdU⁺ cells in (A) splenic and (B) peritoneal B-cell subsets. (C) Absolute numbers of BrdU⁺ MZ B cells in WT versus WASp^−/− mice. Data shown reflect the average of 3 mice per time point and are representative of 2 independent experiments. *P ≤ .05. (D) For cell-cycle analysis, splenocytes from WT or WASp^−/− mice were stained with PyroninY and DAPI in addition to surface markers. Data show the percentage of cells in either S- or G₂/M phase of the cell cycle (average of 3 mice) from one of 3 independent experiments. *P ≤ .05; **P ≤ .01.