Allergic sensitivity confirmed by the release of histamine from small blood samples.

An enzymatic-isotopic microassay that can measure picogram amounts of histamine in 20 microliter samples of plasma has been used to confirm diagnosis of allergic sensitivity to extracts of house dust mite, cat dander, grass, plantain, Cladosporium mould and bee sting venom by the skin test procedure. Multiple assays for allergic histamine release can be performed on minimal blood samples resulting in a qualitative and quantitative prediction of allergic sensitivity from an in vitro biochemical procedure.