Growth Inhibitory Effect of Non-immune Lymphocytes on Tumour Cells, in vitro, in the Absence of Mitogenic Agents

Abstract

LYMPHOCYTES from individuals previously immunized with allogeneic cells destroy such cells in vitro¹. It is generally agreed, however, that lymphoid cells from non-immune donors are not active against allogeneic target cells unless cell contact between the two populations is promoted by the use of phytohaemagglutinin (PHA) or xenogeneic antibody². Most experiments dealing with the consequence of mixing lymphocytes with allogeneic cells have been concerned with determining the presence or absence of target cell death, and only limited attention has been given to assessing the ability of target cells to grow during incubation with aggressor lymphocytes^3,5. We describe here a marked cytostatic effect exerted on B16 mouse melanoma cells by non-immune lymphocytes from C57BL/6 mice in the absence of PHA or other agents which promote cell contact.