Resident pulmonary lymphocytes expressing the γ/δ T-cell receptor

Abstract

THE biological role of cells bearing the γδS T-cell antigen receptor (TCR) is as yet unclear^1-3. Although there are indications that some γδ⁺ cells can mediate cytotoxicity^4-7, their antigen-related functions have not yet been defined. In the mouse, γδ⁺ ceils constitute 1–3% of T cells in lymphoid organs^8,9. Intestinal intraepithelial lymphocytes (lELs) and dendritic epidermal cells (DECs) also appear to carry the γδ TCR^6,10-13. The strategic locations of DECs and lELs have led to the suggestion that γδ⁺ cells could constitute a first line of defence in the vicinity of large surfaces of contact with the environment¹⁴. We report here that an estimated 8–20% of resident pulmonary lymphocytes (RPLs) are CD3⁺αβ TCR⁻, and presumably γδ TCR⁺. Furthermore, mice exposed to aerosols containing a Mycobacterium tuberculosis extract have an increased number of activated CD3⁺αβ-TCR⁻ pulmonary T cells which can be propagated in vitro.