Lymphocytes from lymph nodes at different distances from human melanoma vary in their capacity to inhibit/enhance tumor cell growth in vitro.

Eighty-six lymph nodes at measured distances from a primary tumor were removed from 68 patients with malignant melanoma. The ability of lymph-node lymphocytes (LNL) from these nodes to modulate proliferation of a melanoma cell line (UCLA-SO-M14) in vitro was tested. LNL from the majority of lymph nodes (66%) inhibited M14 growth, but LNL from 34% of nodes stimulated growth of the cell line. Peripheral blood mononuclear cells always inhibited M14 growth. Distance of a node from the primary tumor was found to be an important determinant of LNL activity. This was demonstrated using pairs of nodes from individual patients. In 86% of cases, LNL from nodes located nearer to the tumor inhibited M14 growth less than LNL from more distant nodes. Stimulation of M14 growth was commonest with LNL from nodes located near to the tumor. CD8+ T cells were largely responsible for M14 growth inhibition, whereas CD4+ cells were associated with stimulation of M14 growth. Removal of CD4+ lymphocytes from growth stimulatory LNL resulted in a CD4-depleted LNL preparation that inhibited M14 cell proliferation. The environment in lymph nodes located dose to tumors may thus favor growth of metastatic tumor cells.