Regional variation in the lamina propria T cell receptor V beta repertoire in normal human colon

Lamina propria (LP) T cell populations in the normal human colon contain oligoclonal expansions, but their distribution has not been well studied. We analyzed T cell receptor (TCR) beta-chain (V beta) variable region expression in CD4(+) and CD8(+) peripheral blood T cells and LP T cells from separated colonic segments in 13 subjects. CD4(+) and CD8(+) V beta subset expansions were found in the LP of most individuals, and remarkable differences in CD4(+) and CD8(+) TCR repertoires were apparent between colon and blood as well as between colon segments within each individual. The presence of such T cell expansions in colon therefore cannot be used to infer immunopathology. In addition, CD8(+) V beta expansions seen in peripheral blood T cells, which have been previously shown to be clonal in origin, were also often expanded in LP T cells of the same subject. These results suggest that LP CD8(+) T cell stimulation may contribute to CD8(+) peripheral blood T cell expansions.