The competitive Histamine ELISA kit uses the microtiter plate format. Histamine is bound to the solid phase of the microtiter plate. Acylated histamine and solid phase bound histamine compete for a fixed number of antiserum binding sites. When the system is in equilibrium, free Antigens and free Antigens-antiserum complexes are removed by washing. The antibody bound to the solid phase histamine is detected by anti-rabbit/peroxidase. The substrate TMB / peroxidase reaction is monitored at 450 nm. The amount of antibody bound to the solid phase histamine is inversely proportional to the histamine concentration of the sample. Sample Types: plasma, urine, cell culture. Range: 0.15 - 25 ng/mL. Sensitivity: 0.02 ng/mL. Time: 2.5 hours ? Histamine plays a major role in the initial phase of an anaphylactic reaction. The quantification of histamine in plasma after allergen administration is of clinical interest. Histamine is part of the immune response to foreign pathogens and it increases the permeability of the capillaries to white blood cells and other proteins in order to allow them to engage foreign invaders in the affected tissues. Responsible for the biological effects of histamine in tissue are the activation of different surface receptors, for instance H1, H2 and H3. Histamine is involved in the regulating physiological function in the gut and acting as a neurotransmitter.