Destruction of IgG anti-A sensitized erythrocytes by mononuclear leucocytes from normal and ABO haemolytic disease affected infants.

Studies were undertaken to investigate the antibody-dependent cell-mediated cytotoxicity (ADCC) activity of mononuclear leucocytes (MNL) from cord and healthy adult blood and that from infants with ABO haemolytic disease. The ADCC levels of MNL from both types of newborn blood were found to be higher than that of MNL from adult blood. The extent of ADCC was positively related to the degree of antibody sensitization of the red cells and to the effector cell target cell ratio. The ADCC activity was effected mainly by the adherent cell fraction and could be inhibited by cytochalasin B, hydrocortisone and also by high concentrations (more than 0.5 mg/ml) of non-specific free human IgG. Phagocytosis was also demonstrated to be an important mechanism in the destruction of IgG anti-A coated red cells by the MNL.