Activity of lymphoid cells separated from mammary tumors in blastogenesis and Winn assays.

Lymphoid cells isolated from mouse mammary tumors by isokinetic gradients were not stimulated in vitro by either phytohemagglutinin or a soluble, tumor-associated antigen extract even though splenocytes from the tumor-bearing mice were responsive to both. In in vivo Winn assays, lymphoid cells isolated from tumors markedly stimulated tumor growth rate. The effect on growth rate was abrogated by exposure of the isolated lymphoid cells to antilymphocyte serum and complement.