Immunogenetics of human haptoglobins

Variations in the cerebrospinal fluid proteome following traumatic brain injury and subarachnoid hemorrhage

“…The α-chain has two different isotypes (α 1 and α [2]), both encoded on chromosome 16q. Population expression of the different α alleles is distributed widely among different ethnic groups [175][176][177][178]. Synthesis is primarily in the liver, with baseline levels in the range 0.4-1.5 mg/mL of plasma, although minor contributions have also been demonstrated from the spleen, lymph nodes, and thymus [179].…”

“…The remarkably stable Hp-Hb complex is then consumed by circulating monocytes and reticuloendothelial macrophages bearing the CD163 Hb scavenger receptor for degradation and recycling of the heme moiety [180][181][182]. This process is relatively linear at higher concentrations (15 mg/100 mL/h), but is more exponential at physiologic concentrations, with a half-life of 9-12 min [178]. Severe intravascular hemolysis can quickly overwhelm the ability of plasma Hp to remove free Hb, as no positive feedback loop exists for increased synthesis.…”