Componentsforthein-vitrodiagnosticquantitativedeterminationofhistaminereleaseinheparinizedwholeblood.Inhumans,histamine(ß-imidazoleethylamine)isthemostimportantmediatorandismostlyfoundintheinitialphaseofananaphylacticreaction("immediatetype"allergy).Histamineisbiosynthesizedbyenzymaticdecarboxylationofhistidine.Intheorganism,histamineispresentinnearlyalltissues,anditismainlystoredinthemetachromaticgranulaofmastcellsandthebasophilicleukocytes.Itispresentinaninactiveboundformandisonlyreleasedasrequired.
Ofclinicalinterestinthehistaminedeterminationisthequantificationofthehistaminereleasefrombasophilicleukocytesinallergiesofthe"immediatetype"aswellasofthehistaminequantitywhichispresentinvariousbodyfluids(plasma,urine,cellculturesupernatants),afterallergenadmiNISTration.Firstcontactoftheorganismwithanallergendoesnotresultintheinitiationofahistaminerelease.First,specificIgEantibodiesareproducedwhichmigratetothemastcellsandtheretheybindtothereceptors.Atthesecondallergencontact,atransformationofaBcelltoaplasmacellisnolongerrequired.TheallergendirectlymovestotheIgEantibodiesalreadyboundtothemastcellsandbindstotheseantibodies.Themastcellrespondsbyhistaminesecretionfromitsgranula.