type II hypersensitivity, complement-dependent hypersensitivity to foreign cells or to alterations of cell-surface antigens that is mediated by immunoglobulin G (IgG) or IgM causing immediate destruction of cells, as seen in hemolytic disease of the newborn and in severe transfusion reactions. A second type of type II hypersensitivity is called antibody-dependent cell-mediated cytotoxicity (ADCC). Here IgG- or IgM-coated cells are recognized by natural killer cells, and macrophages are subsequently killed. Also called cytotoxic anaphylaxis.
