Rapid but reversible disappearance of peritoneal B cells induced by FTY720. (A) PerC cells were isolated 10 hours after injection of FTY720 (right) or mock (left), and cell populations were analyzed using flow cytometry. The data are representative of 5 independent experiments. (B) Cell numbers of B220⁺CD11b⁺ B1 B cells and B220⁺CD11b⁻ B2 B cells were calculated by using the total cell number and flow cytometric data. The error bars are ± SEM (n = 5). (C-D) At each time point after FTY720 injection, PerC cells were analyzed by flow cytometry (○, B220⁺CD11b⁺ B1 B cells; •, B220⁺CD11b⁻ B2 B cells). The data represent the mean ± SD (n = 4).