Detection of IgE antibodies to suxamethonium after anaphylactoid reactions during anaesthesia.

Choline covalently coupled to an insoluble support was used in a radioimmunoassay to detect IgE antibodies to suxamethonium in serum samples from patients who experienced life-threatening anaphylactoid reactions after receiving the drug. Direct binding and inhibition experiments and correlations with clinical findings showed that use of choline in such an assay is relevant to the detection of suxamethonium-reactive antibodies. IgE antibodies were found in 9 of 10 patients who reacted to suxamethonium and whose skin-tests to the drug were positive and in 8 other patients who had reactions to other muscle-relaxant drugs. The positive reactions in the latter group were probably due to cross-reacting antibodies that recognise quaternary ammonium groups on more than one muscle relaxant.