Distinct antigen receptor repertoires of two classes of murine epithelium-associated T cells

T LYMPHOCYTES are found not only as recirculating cells in the lymphoid system, but also as immobile cells in certain epithelia. T-cell antigen receptors (TCR) of both α / β and γ / δ-heterodimer subtypes can exhibit an extremely high degree of diversity. The diversity of α / β TCRs derives from the use of a large number of variable (V) gene segments, as well as junctional diversity generated during rearrangement of these segments, whereas the diversity of γ / δ TCRs derives largely from junctional elements, with a smaller contribution from a limited number of V gene segments¹. Many T cells in the epidermal and intestinal epithelia of mice express TCR composed of γ / δ heterodimers^2-5,14,15. We demonstrate here that γ/δ TCRs of T cells in both these tissues are restricted in V gene usage, with different elements predominating. The TCR junctional diversity of epidermal T cells, however, is extremely limited, whereas that of intestinal T cells is extremely diverse. The distinctive features of these two populations suggest that they develop or are selected differently for particular tissue-specific functions.