Decreased reactivity of peritoneal B cells to FTY720 in aly mice. Cells were isolated from the peritoneal cavities of WT (A) or aly (B) mice 12 hours after single or multiple (that is 5) injections of FTY720 (right) or vehicle only (mock; left), and cell populations were analyzed by flow cytometry. The data are representative of at least 4 independent experiments. The numbers of B220⁺CD11b⁺ B1 cells and B220⁺CD11b⁻ B2 cells were calculated from the total cell number and flow cytometric data. Data are presented as mean plus or minus SEM (n = 4). *P < .01; **P < .05.