Absence of correlation between T-lymphocyte activity and development of carcinogen-induced skin tumor in mice

Splenic lymphocytes obtained from female ICR/JCL mice, which had received combined radiation and chemical treatment for induction of skin tumors on their back skin, were tested for their ability to undergo proliferative response to non-specific mitogens as well as to allogeneic lymphocytes in vitro during 18 months after carcinogenic treatment. The treated mice, 168 in all, were divided into three groups: (a) 53 mice with no tumor, (b) 30 mice with skin papilloma, and (c) 85 mice with malignant skin tumor. Control mice, 39 in all, received no treatment. The local carcinogenic treatments used in this study induced a relatively long-lasting suppression of T-cell activities as detected by proliferative response to mitogens. Nevertheless, there was no significant difference in T-cell activities among the three groups of mice that developed (a) no tumor, (b) skin papilloma, or (c) malignant skin tumor. The results obtained with proliferative response to allogeneic lymphocytes were essentially similar. A preliminary study on the induction of cytotoxic T cells from splenic lymphocytes against allogeneic target cells in vitro also indicated that mice which developed tumors were not necessarily the ones which manifested reduced cytotoxic T-cell activity. These results suggest that reduced T-cell function was not a direct cause or not even a prerequisite for development of skin tumors in ICR mice.