IgG-dependent clearance of red blood cells in IgG myeloma patients.

Red blood cells sensitizied with IgG antibodies are rapidly cleared from the circulation of myeloma patients, in spite of serum IgG concentrations several times higher than normal. In contrast, in vitro phagocytosis and cytotoxicity of IgG-sensitized erythrocytes are inhibited by dilutions of normal fresh serum. It is concluded that the current explanantions derived from in vitro experiments are insufficient to explain the IgG-dependent clearance of red blood cells.