CD4- and TCRalphabeta-positive T lymphocytes predominantly infiltrated into well-moderately differentiated colon...

Intraepithelial T lymphocytes have been reported as being functional in the growth of epithelial cells and also in the discrimination of aberrant cells, whereas their function against colon adenocarcinoma cells is obscure. The phenotype of colon intraepithelial T lymphocytes has been found in patients with inflammatory bowel diseases but not in patients with colon adenocarcinoma. In this study, we investigated cell surface markers of tumor-infiltrating T lymphocytes of adenocarcinoma of the colon and rectum at various grades of differentiation and intraepithelial T lymphocytes of adjacent normal colon by enzyme immunostaining. Among intraepithelial T lymphocytes of the normal colon, CD8-and TCRgammadelta-positive T lymphocytes were predominant as described. In contrast, tumor-infiltrating T lymphocytes of well-moderately differentiated adenocarcinoma of the colon and rectum were predominantly CD4- and TCRalphabeta-positive. The decrease of TCRgammadelta-positive T lymphocytes and the increase of CD4 and TCRalphabeta-positive T lymphocytes in adenocarcinoma tissues of the colon and rectum suggests that an alteration of the local immune system participates in the formation of adenoma and/or adenocarcinoma of the colon and rectum, resulting in infiltration of CD4-positive T lymphocytes that have certain activity against transformed cells.