Selective induction of T-cell subsets capable of accelerating and retarding Lewis lung carcinoma

The influence of three T-cell subsets on tumor growth was studied. The first, induced by a thymic microenvironmental fraction, accelerated the appearance of Lewis lung carcinoma in Winn assay. The second subset, derived from the first by incubation with a thymic hormone preparation, had a marked retarding effect on tumor appearance. The third subset, also induced by thymic hormone, but directly from bone marrow precursors, does not appear to influence tumor cells.