We repeated these experiments with alloreactive Ceacam1-Tg T cells and as expected, observed a decrease in numbers of CFSE lo T cells as assessed by CFSE dilution ( Figure 6E ). This is consistent with an inhibitory role for Ceacam1 in the proliferation of alloreactive T cells. However, we did not observe significant differences in alloactivation between Ceacam1-Tg vs. WT donor T cells (data not shown).