Association of haptoglobin phenotypes with ceruloplasmin ferroxidase activity in β-thalassemia major

Background: Haptoglobin (Hp) and ceruloplasmin (CP) are 2 plasma antioxidants playing a role in preventing iron-induced oxidative damage. This study presents data related to Hp phenotypes and ceruloplasmin ferroxidase activity in relation to iron store markers in patients with β-thalassemia major.

Methods: Blood specimens were collected from 196 subjects (124 β-thalassemia major patients and 72 healthy controls). Serum levels of iron, total iron binding capacity (TIBC), ferritin, high sensitivity C-reactive protein (hs-CRP), ceruloplasmin, and ferroxidase activity were determined using conventional methods. Haptoglobin phenotypes were determined by polyacrylamide gel electrophoresis.

Results: As expected, the mean levels of iron store markers, except TIBC, were significantly higher in patients than in controls. Ceruloplasmin concentrations (mg/dl) and its ferroxidase activity (U/l) were significantly higher in patients than in controls (57.9±18.8 vs 46.9±14.2 and 159.9±47.8 vs 95.3±20.9; p<0.001, for CP and Hp, respectively). As for Hp phenotypes, no significant differences were observed between iron store markers and ferroxidase activity among the control group. In the patients group however, significantly higher concentrations of ceruloplasmin and its ferroxidase activity were observed among patients with Hp2-2 phenotype as compared to patients with the other phenotypes. Additionally, correlations according to Hp phenotypes revealed strong association between ceruloplasmin ferroxidase activity and serum ferritin in patients with Hp 2-2 phenotype and not in the others (r=0.331, p<0.05).

Conclusion: Thalassemia patients with Hp 2-2 phenotype are under greater iron-driven oxidative stress than patients with other phenotypes.