CD200R1 and colon adenocarcinoma: Co-stimulation of IL-2 stimulated T-IEL with anti-CD3 and iSEC1 or CD200 negatively affected IFNγ and TNFα production and inhibited T-IEL cytotoxic activity against a murine colonic adenocarcinoma cell line.102 These results suggest that CD200R1 binding to its ligands negatively regulates T-IEL functions, similar to its function on DETC.103 Further studies are awaited to address if CD200R1 signaling impacts intestinal T-IEL function in vivo, and whether iSEC1 and iSEC2 are the main ligands driving CD200R1 activation.