SPONTANEOUS AND INDUCED CYTOTOXIC PROPERTIES OF HUMAN ADHERENT MONONUCLEAR-CELLS - KILLING OF NON-SENSITIZED AND ANTIBODY-COATED NON-ERYTHROID CELLS

Abstract

Human adherent mononuclear cells have a strong capacity to kill human nucleated target cells. Cytotoxicity was measured by the release of 51Cr from 2 established cell lines. Freshly prepared monolayers killed non-sensitized and antibody-coated K562 [human neoplastic pleural effusion cells] and CLA-4 [human lymphocytic] target cells. These spontaneous events decreased after short term culture. A 2nd peak of cytotoxic activity was induced by activating the effector cells with [Salmonella enteritidis] endotoxin-treated serum or phytohemagglutinin. Cytotoxicity was inhibited by silica particles. Studies with .alpha.-naphthyl esterase showed that 95% of freshly prepared cells and 99% of monolayers cultured for 68 h were monocytes. Adherent monocytes may be the predominant cytotoxic effector cell, although a contributing effect by the small numbers of contaminating lymphocytes cannot be excluded. Evaluation of monocyte cytotoxicity has a useful role in clinical investigation.