FIGURE 5.

Peritoneal B1a cells gain CD6 expression outside the peritoneal cavity. A, splenocytes from WT and CD6^−/− mice were isolated, and CD6 expression was analyzed on migrant peritoneal B1a cells in the spleen by gating on CD19⁺ CD5⁺ double-positive cells (B1a cells) and then assessing the expression of CD6 on B1a cells that are CD11b positive (migrant peritoneal B1a cells). Data are representative of 10 independent experiments. The solid line indicates CD6 background expression on migrant peritoneal B1a cells from CD6^−/− mice, and the dotted line indicates CD6 expression on WT migrant peritoneal B1a cells. B, peritoneal cells from WT mice were isolated and labeled in vitro with CFSE. These labeled peritoneal cells were adoptively transferred into the peritoneal cavity of CD6^−/− recipient mice. LPS was administered to these mice 2 h post-adoptive transfer, and CD6 expression was analyzed on migrated peritoneal B1a cells in the spleen 72 h later by gating on CFSE⁺, CD19⁺, and CD5⁺ cells. Data are representative of n = 4. The solid line indicates CD6 expression on CFSE-labeled peritoneal B1a cells from the CD6^−/− mice that migrated to the spleen of CD6^−/− mice, and dotted line indicates CD6 expression on CFSE-labeled WT peritoneal B1a cells that migrated to the spleen of CD6 ^−/− mice.