When we analyzed organs of recipients of allografts containing WT vs. Ceacam1-Tg T cells, we noted decreased numbers of donor effector T cells in the MLN, PLN, and liver ( Figure 3B ). Via histopathological analysis, we also observed decreased numbers of total lymphocytic infiltrates into the liver, small and large bowels by histopathology ( Figure 3B ), as well as decreased neutrophilic infiltrates in these organs (data not shown). Finally, we assessed infiltrating T cells in WT and Ceacam1 2/2 allo-BMT recipients, and observed increased numbers of donor alloactivated effector T cells in the MLN and IEL of Ceacam1 2/2 allo-BMT recipients, but decreased numbers of these cells in the PLN and liver ( Figure 3C ). Ceacam1 regulates the sensitivity of the small intestine to radiation injury