HNY to all,
IgE antibodies to morphine (generally available as Phadia RAST) bind its single substituted ammonium group. They also bind neuromuscular blocking drugs at their substituted ammonium ions. The function of the test is to detect such antibodies in the investigation of anaphylaxis during general anaesthesia. Morphine itself single binding site for IgE and it cannot therefore cross-link IgE on the mast cell surface. If the clinical problem is rash or hypotension with opiates, it is likely due to a direct effect of the opiate on the mast cell and detection of IgE to morphine or other opiate would not be useful.
Robert Puy
