An enzymatic-isotopic microassay for measuring allergic release of histamine from blood and mast cells in vitro.

An enzymatic-isotopic microassay has been developed which has the sensitivity and specificity to measure picogram amounts of histamine in 20 microliter samples of plasma. This analytical technique has been used to study the allergic release of histamine in vitro in whole human blood. Prior separation of leucocytes is not necessary and multiple assays can be performed on minimal blood samples making the procedure attractive as a diagnostic procedure in allergy. The enzymatic-isotopic microassay is versatile in that it has also been applied to the study of all allergic release of histamine from rat peritoneal mast cells.