Lymphocyte In Vitro Cytotoxicity: Correlation of Derepression with Release of Lymphotoxin from Human Lymphocytes

Abstract

The release of lymphotoxin by PHA-activated normal human lymphocytes in vitro has the following characteristics: release begins within 2 to 3 hr after derepression, long before any evidence of morphologic alteration; initiation occurs rapidly upon exposure to PHA; once initiated, release continues for long periods in culture; and LT release requires lymphocyte energy metabolism and protein synthesis, but is independent of cellular DNA synthesis. Immune and normal lymphocytes from several animal species can be induced in vitro to release LT-like materials by a variety of agents. It appears that all these reagents react to some degree with structures (receptors) present on the lymphocyte surface, indicating that a common mechanism may operate in cellular responses involving tissue destruction. The relationship between LT release and lymphocyte transformation is discussed, as well as a postulated role for LT as an effector molecule in cellular immune responses.