Over-utilization of the J delta 3 gene-segment in Crohn's disease

Abstract

A majority of normal human intestinal intraepithelial lymphocytes (iIEL) are CD8+, express the alpha beta-T cell receptor (TCR) and are oligoclonal. The remainder of normal iIELs, which are also oligoclonal, express the gamma delta-TCR and preferentially utilize variable regions (V delta 1 and V delta 3) which are different from adult peripheral blood lymphocytes (V delta 2). The junctional region usage of gamma delta-TCRs in intestinal diseases is largely unknown. The aim of this study was to examine gamma delta-T cell clonality and junctional region usage of V delta 1 and V delta 3 transcripts in Crohn's Disease (CD) in comparison to several other chronic inflammatory diseases of the colon by polymerase chain reaction amplification, cloning and sequencing. As previously observed in normal subjects, all inflammatory cases examined, including CD (n = 3), ulcerative colitis (n = 1), diverticulitis (n = 1) and lymphocytic colitis (n = 1), the V delta 1 and V delta 3 transcripts contained reiterated sequences consistent with the expansion of gamma delta-T cells expressing these receptors. In 2/3 CD cases, but none of the non-CD inflammatory cases, transcripts containing J delta 3, a rarely used J delta, was observed among the V delta 1 and/or V delta 3 transcripts. Thus, in a subset of CD, gamma delta-T cells expressing J delta 3 may be expanded implicating a role for unique ligands that drive the expansion of T cells expressing these receptors.