Which acute-phase reactant is most closely associated with binding free hemoglobin and limiting oxidative damage?

Which acute-phase reactant is most closely associated with binding free hemoglobin and limiting oxidative damage?

• A. Haptoglobin
• B. Fibrinogen
• C. Ceruloplasmin
• D. Serum amyloid A

Answer: (A)

Acute-phase proteins include scavenger proteins that help neutralize harmful byproducts of inflammation. The one that directly handles free hemoglobin released during intravascular hemolysis is haptoglobin. It binds free hemoglobin with high affinity to form a haptoglobin–hemoglobin complex, which prevents the heme iron from catalyzing oxidative reactions and protects the kidneys from Hb-induced oxidative damage. The complex is then cleared by macrophage receptors, limiting oxidative stress and iron loss. In inflammation, haptoglobin levels can rise, but in the setting of significant intravascular hemolysis, levels may fall because haptoglobin is consumed by binding free Hb. Other acute-phase proteins like fibrinogen (involved in coagulation), ceruloplasmin (a copper-containing oxidase), and serum amyloid A (an inflammatory marker) do not specifically bind free hemoglobin to curb oxidative damage.

Acute-phase proteins include scavenger proteins that help neutralize harmful byproducts of inflammation. The one that directly handles free hemoglobin released during intravascular hemolysis is haptoglobin. It binds free hemoglobin with high affinity to form a haptoglobin–hemoglobin complex, which prevents the heme iron from catalyzing oxidative reactions and protects the kidneys from Hb-induced oxidative damage. The complex is then cleared by macrophage receptors, limiting oxidative stress and iron loss. In inflammation, haptoglobin levels can rise, but in the setting of significant intravascular hemolysis, levels may fall because haptoglobin is consumed by binding free Hb. Other acute-phase proteins like fibrinogen (involved in coagulation), ceruloplasmin (a copper-containing oxidase), and serum amyloid A (an inflammatory marker) do not specifically bind free hemoglobin to curb oxidative damage.