Cytotoxic Effects of Activated Human Monocytes and Lymphocytes to Anti-D-treated Human Erythrocytes in Vitro

Incubation of human monocytes, derived from peripheral blood, with cell-free supernatants from mixed lymphocyte cultures resulted in morphological and functional changes in the mature macrophages. Activation of monocyte-derived macrophages by these factors resulted in a significant increase in their capacity to lyse anti-D-treated human erythrocytes. The lytic activity of both normal and activated macrophages appeared to be independent of erythrophagocytosis. T lymphocytes activated by either allogeneic cells or the mitogen phytohaemagglutinin were not cytolytic to treated erythrocytes even at high effector to target cell ratios.