Thymus-dependent lymphocyte function in dimethylnitrosamine-induced renal carcinogenesis is not depressed.

As one measure of cell-mediated immunity, the blastogenic response of enriched spleen lymphocytes to phytohaemagglutinin (PHA) was assayed at sequential daily and weekly intervals following the administration of dimethylnitrosamine (DMN) as a single dose sufficient to induce renal tumours in 100% of surviving rats. PHA responsiveness of DMN-treated rats was not suppressed at any stage of tumour induction in contrast to rats which had been intentionally immunodepressed by neonatal thymectomy. It was concluded that DMN is unlikely to facilitate the cancer process by impairing thymus-dependent lymphocyte function.