A biogenic amine mediates effects via 4 receptors including H2 receptor.
Histamine acts via H1 and H2 receptors to cause vasodilatation and vascular permeability.
Histamine acts through H3 receptors affecting neurogenic vasodilatation through local neuron-mast-cell feedback loops.
Binding of H2 receptors with histamine inhibits NADPH oxidase production of oxygen radicals, which can impair immune functions of cytotoxic lymphocytes.
Can upregulate cytokines, inhibit tumor necrosis factor-α, enhance the killing affect of cytotoxic lymphocytes, increase T-cell lymphocytes and increase the production of γ-interferon.
In combination with IL-2 increases the survival in patients with melanoma and liver metastases.