Haptoglobin Polyclonal antibody

Haptoglobin is also named as Zonulin and belongs to the peptidase S1 family. Haptoglobin is an alpha-2-glycoprotein synthesized mainly by hepatocytes consisting of both alpha and beta subunits linked by disulfide bonds forming dimers (PMID: 4018023). Haptoglobin is primarily produced in the liver, and when red cells are lysed in vivo, free hemoglobin binds to circulating haptoglobin; the hemoglobin-haptoglobin complex is then degraded by the reticuloendothelial system (PMID: 24809098). Because haptoglobin levels become depleted in the presence of large amounts of free hemoglobin, decreased haptoglobin is a marker of hemolysis. The human haptoglobin (HP) gene exists in two major allelic forms leading to three major genotypes: Hp1-1, Hp2-1, and Hp-2-2, that separate on alkaline starch gel electrophoresis due to different molecular weights (PMID: 17474882). Their properties vary in binding strength, anti-oxidative ability, and rate of clearance. Binding strength is greatest with Hp1-1, but the Hp-2 genotypes can bind a larger number of hemoglobin alpha-beta dimers. Complexes of Hp2-2 and hemoglobin have higher affinity for the CD163 receptor, the monocyte-macrophage receptor that facilitates its clearance. Neutrophils contained a large amount of highly glycosylated Hp (β-chain 45-65 kDa) synthesized in neutrophil precursors and stored in specific granules and a small amount of Hp (β-chain 39 kDa) endocytosed from plasma and stored in secretory vesicles (PMID: 16543473).