Intraepithelial T-Cells of the TcRτ/δ+CD8- and Vδ1+ Phenotypes are Strikingly Increased in Coeliac Disease

Abstract

The increased density of jejuna] intraepithelial lymphocytes (IEL) in coeliac disease (CD) is interesting in view of the possible T-cell involvement in the pathogenesis. In human peripheral lymphoid tissues and blood, about 95% of T-cells express the α/β T-cell receptor (TCRα/β). A second TCR termed τ/δ has been identified on a minor fraction of peripheral T-cells which are mostly CD4-8- (“double negative”). Human IEL have recently been shown to be mostly of the TCRα/β+CD8+ phenotype with only a small fraction of the TCRτ/δ variety. We have studied the expression of the TCRτ/δ on CD3+ IEL in situ by two-colour immunofluorescence on jejunal tissue sections from 24 patients with CD and 17 controls. The proportion of intraepithelial TCRτ/δ cells was significantly increased (p<0.002) in untreated (median 20%, range 11–53%) and treated CD (median 23%, range 16–55%) compared with controls (median 2%, range 0–39%). This subset was preferentially located within the epithelium rather than in the lamina propria. Paired staining showed that most (~90%) intraepithelial TCRτ/δ+ lymphocytes were CD8- in CD, and a remarkably large fraction (medain 67% range 58–94%) expressed the Vδ1/Jδ1 or Vδ1/Jδ2-encoded epitope (MoAb δTCS1 +). The intraepithelial TCRτ/δ+CD8-T-cell subset thus shows a particular association with CD.