It has long been assumed that histamine plays a role in allergic reactions and that it may in part be responsible for many of the clinical symptoms in allergy. The actual experimental evidence for this hypothesis, however, is meager and circumstantial. It is, on the whole, based on the similarity between the allergic and the histamine cutaneous reactions and on some similarities between allergic attacks and the systemic effects of histamine injections. To our knowledge, the presence of a histamine-like substance after application of allergen to tissues from sensitized patients has not been demonstrated convincingly.
An experimental approach to the study of histamine1 release in allergy suggested itself from observations on anaphylaxis which one of us has made recently.2 It was found that blood cells from sensitized animals released part of their histamine into the plasma when brought into contact in vitro with the antigen. Extensive experimentation has