“SPONTANEOUS” CYTOLYSIS BY NORMAL HUMAN LYMPHOCYTES OF BURKITT'S LYMPHOMA CELLS OF THE EB₂ CELL LINE

Abstract

Summary Previous studies have shown that non‐sensitised lymphocyte preparations can kill antibody‐coated allogeneic lymphoma cells. During these studies on antibody‐induced lymphocyte‐mediated cytotoxicity it was observed that lymphocyte preparations from most normal humans tested were highly cytotoxic even to non‐antibody‐coated lymphoma cells of a particular cell line (EB 2 ) but not to a second lymphoma cell line (CLA 4 ), or to allogeneic normal lymphocytes. In contrast, if the target cells were coated with antibody, normal lymphocyte preparations killed EB 2 cells, CLA 4 cells and allogeneic lymphocytes, with equal facility. This non‐antibody‐dependent “spontaneous” cytotoxicity towards EB 2 cells occurred even at low lymphocyte:EB 2 ratios (< 10:1) and was not mediated by lymphotoxin. “Spontaneous” anti‐EB 2 lymphocytotoxicity was increased rather than blocked in the presence of specific anti‐EB 2 serum. The possible relationship between “spontaneous” cytolysis of EB 2 cells and sensitization to EB virus is discussed.