A new subpopulation of intestinal intraepithelial lymphocytes expressing high level of T cell receptor γδ

The murine intestinal epithelium contains T cell receptor (TcR) γδ‐bearing T cells in high frequency. In the present report, we showed that TcR γδ‐bearing intestinal intraepithelial lymphocytes (IEL) from C3H/He (H‐2^k) mice can be divided into two subpopulations based on TcR expression level; a subpopulation with a remarkably high level of TcR expression and a subpopulation with a moderate level of TcR expression, designated as TcR γδ^hi IEL and TcR γδ^mod IEL, respectively. In flow cytometric analysis, the TcR γδ^hi IEL expressed a high level of TcR (mean fluorescence channel 518) when compared with the TcR level of TcR γδ⁺ T cells in other lymphoid organs (mean fluorescence channel 88). The TcR γδ^hi IEL were detected in IEL from mice of H‐2^k and H‐2^k/b haplotypes but not in H‐2^b and H‐2^d haplotypes. V_δ4, which was reported to be frequently expressed in IEL of H‐2^k mice, was preferentially expressed by TcR γδ^hi IEL. These results suggested that the existence of the TcR γδ^hi population is related to the high frequency of V_δ4 in H‐2^k mice.