Histamine release inhibition in vitro and antianaphylactic effects in vivo of some chemical compounds.

Several different types of compounds inhibited the release of histamine from the "platelet fraction" of rabbit blood when antigen was added to the blood of a sensitized rabbit in vitro. These compounds were all very toxic in vivo and could be tested only at low levels for their ability to protect animals against anaphylaxis. None of the compounds gave significant protection to sensitized animals when antigen was given intravenously. Three compounds protected animals against antigen administered as an aerosol. None of these showed any promise of clinical usefulness.Of a number of compounds which have been reported to alleviate allergic symptoms, or to protect against anaphylaxis, none prevented the release of histamine in vitro to any considerable extent.