Diversity of γδ T-cell receptors on murine intestinal intra-epithelial lymphocytes

THE search for the genes encoding the T-cell receptor (TCR)α -and β-subunits revealed a third gene γ which shares with the α-and βgenes several properties including somatic rearrangement1,2. This gene, together with a fourth rearranging gene δ3,4, encodes a second type of T-cell receptor, TCR γδ5–8. Although TCR γδ-bearing T cells constitute a relatively minor subpopulation in the thymus and in peripheral lymphoid organs8,9, they are the major lymphocytes of epidermis (dendritic epidermal cells or DEC)10 and of intestinal epithelium (intestinal intraepithelial lymphocytes or IEL) in mice11,12, suggesting that at least some γδ T cells are important in the surveillance of a variety of epithelia13. It was recently reported, however, that the TCR γδ on DEC has essentially no structural diversity, implying that the putative ligand is monomorphic14. As this finding, if generally applicable, poses severe restrictions on the origin of the ligand, we investigated the diversity of the TCR on the second major epithelium-associated γδ T cells, namely IEL from mice. We report here that by contrast with the DEC γδ, the IEL γδTCR are structurally diverse.