Immunofluorescence detection of drugs in postmortem tissues: a new technique with potential for assessment of drug influence in cause of death.

This report describes a new technique, immunofluorescence, for the detection and possible characterization of drug content in postmortem tissues. By using antisera generated against a drug-protein conjugate, the stabilization of tissue-sequestered drug is accomplished by incubation of fresh frozen sections of tissue with dilute solutions of rabbit anti-drug antibodies. Secondary incubation with a fluorescence-labeled anti-rabbit immunoglobulin labels these points of sequestration. Tissue sections so stained are examined by fluorescence microscopy. In studies with rats given graded doses of morphine sulfate, there were discernible differences in tissue binding of morphine in brain sections from animals treated "therapeutically," fatally, and chronically. Extension of these studies to human autopsy material is anticipated and potential problems are discussed. This technique offers the forensic toxicologist the potential for evaluating the drug content of tissues in situ.