Histamine Receptor Antibodies

Histamine is an ubiquitous chemical messenger that can be released from a variety of cells (e.g. mast cells, enterochromaffin-like cells, neurones) to act on one of four histamine receptors: H1, H2, H3 and H4. The classification of histamine receptors has resulted from rigorous pharmacological analysis of the response of different isolated tissues and cells to histamine. Cloning techniques have identified the amino acid sequence of the human H1, H2, H3 and H4 receptors, and they are all members of the G protein-coupled receptor superfamily. The primary mechanism by which H1 receptors produce functional responses is via Gq/G11-mediated activation of phospholipase C (PLC) and Ca2+ mobilisation, whilst H2 receptors couple positively to adenylate cyclase via Gs, leading to the formation of cAMP. The signal transduction pathway used by the H3 receptor appears to be via Gi and Go proteins. The H4 receptor regulates similar signalling mechanisms to the H3 receptor, including inhibition of adenylyl cyclase, mobilisation of calcium from intracellular stores and stimulation of MAP kinase in both heterologous expression systems and native immune cells.