Cytotoxic α/β⁺ and γ/δ⁺ T cells in murine intestinal epithelium

Murine intraepithelial lymphocytes (IEL) consist of two main populations. Approximately half are Thy-1+, most of which are CD3+, T cell receptor (TcR) alpha/beta+, and the remainder are Thy-1-, most of which are CD3+, TcR alpha/beta- (presumably TcR gamma/delta+). In redirected cytotoxicity assays, TcR alpha/beta+ IEL are potent cytotoxic effectors. Thy-1-, CD3+, TcR alpha/beta- IEL isolated from athymic mice are also cytotoxic. Thus, regardless of TcR usage or Thy-1 expression, IEL are cytotoxic effectors.