T cell receptor-bearing cells among rat intestinal intraepithelial lymphocytes are mainly α/β+ and are thymus dependent

Rearrangement of both the β and γ chain T cell receptor (TcR) genes was detected in intestinal intraepithelial lymphocytes (IEL) from normal euthymic rats. Flow cytometric analyses showed that about 73% of the IEL were CD3+ (1F4) and that67% were TcR α/β+ (R73). About 5% of the IEL were found to be CD3+, TcR α/β− in double-labeling experiments suggesting that a small fraction of IEL in the rat express the alternative TcR γ/δ. More than 70% of the IEL were granular implying that many CD3+ IEL are granular. In IEL from athymic nude rats no rearrangement of either the TcR β or γ chain genes or surface expression of CD3 or TcR α/β was detected despite the fact that about 95% of the cells were granular and morphologically similar to those in normal rats. Taken together our data suggest that the majority of IEL in the rat express the conventional TcR α/β and that TcR-bearingcells in the gut epithelium are thymus dependent