Overview
- Peptide HTLFEWDFGKEIC, corresponding to amino acids 75-87 of human HRH4 (Accession Q9H3N8). 1st extracellular loop.
- Human promyelocytic leukemia (HL-60) and chronic myelogenous leukemia (K562) cell lysates (1:400).
Western blot analysis of human chronic myelogenous leukemia (K562) (lanes 1 and 3) and human promyelocytic leukemia (HL-60) (lanes 2 and 4) cell lysates:1,2. Anti-Human Histamine H4 Receptor (HRH4) (extracellular) Antibody (#AHR-004), (1:400).
3,4. Anti-Human Histamine H4 Receptor (HRH4) (extracellular) Antibody, preincubated with Human Histamine H4 Receptor/HRH4 (extracellular) Blocking Peptide (#BLP-HR004).
- Live intact acute T-cell leukemia (Jurkat) cell line (1:20).
- The blocking peptide is not suitable for this application.
Histamine (2-[4-imidazole]ethylamine) is a low-molecular-weight amine synthesized from L-histidine. It is produced by various cells throughout the body, including central nervous system neurons, gastric mucosa parietal cells, mast cells, basophils and lymphocytes. Histamine is a major biological mediator whose functions include, among many others, regulation of vascular smooth muscle, immune regulation, regulation of sleep-wake cycles and regulation of gastric acid secretion.1
The biological effects of histamine are mediated through four receptors (H1- H4 receptors) all of which belong to the 7-transmembrane domain, G protein-coupled receptor (GPCR) superfamily.
Histamine H4 receptor couples to Gi/G0 proteins and receptor activation leads to inhibition of adenylate cyclase, mobilisation of calcium from intracellular stores and activation of the mitogen-activated protein kinase (MAPK) cascade.1,2
Histamine H4 receptor is largely expressed in haemopoietic cells including mast cells, eosinophils, dendritic cells and T lymphocytes. H4 receptors modulate eosinophil migration and the selective recruitment of mast cells leading to amplification of histamine-mediated immune responses. In addition, H4 receptors are involved in dendritic cell activation and the regulation of T lymphocyte cytokine production.2,3
