Similar expression of S1P₁ and biologic reactivity to S1P among various populations of aly peritoneal B cells. (A) Quantitative RT-PCR analysis for S1P₁ expression was performed using RNA isolated from sorted splenic B (□), and peritoneal B1 () and B2 (■) cells. The relative quantity of specific mRNA encoding S1P₁ was expressed as a ratio to GAPDH. Data are expressed as the mean plus or minus SD of 4 mice. (B) In vitro migration assay was performed with peritoneal B1 (○) and B2 (•) B cells purified from WT (left) and aly (right) mice. Peritoneal B cells were added to the upper chamber of a transwell plate in the presence of 0, 20, 200, or 2000 nM S1P in the lower chamber. Six hours later, the number of cells that had migrated into the lower chamber were counted. Data are representative of 3 independent experiments. (C,D) CFSE-labeled aly peritoneal B cells were adoptively transferred into SCID mice by the intraperitoneal (C) or intravenous (D) routes: reconstituted SCID mice were treated simultaneously with (right panels) or without (left panels) FTY720. After 12 hours, cells were isolated from the peritoneal cavity for the analysis of CFSE⁺ B220⁺ cells. Data are representative of 4 independent experiments.