Sudden death caused by interaction between a macroglobulin and a divalent drug.

Intravenous injection of the divalent X-ray contrast medium ioglycamic acid ("Biligram") induced intravascular precipitation and sudden death of a patient owing to reaction with his monoclonal macroglobulin. Mice reacted similarly in passive transfer experiments. The corresponding monovalent compound, acetrizoic acid, was also bound to the IgM but did not induce precipitation and had no apparent ill-effects on mice in passive transfer experiments.