Diversity of γδ T-cell receptors on murine intestinal intraepithelial lymphocytes

Abstract

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 rearrangement^1,2. This gene, together with a fourth rearranging gene δ^3,4, encodes a second type of T-cell receptor, TCR γδ^5–8. Although TCR γδ-bearing T cells constitute a relatively minor subpopulation in the thymus and in peripheral lymphoid organs^8,9, they are the major lymphocytes of epidermis (dendritic epidermal cells or DEC)¹⁰ and of intestinal epithelium (intestinal intraepithelial lymphocytes or IEL) in mice^11,12, 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.