Haptoglobin phenotypes and plasma haptoglobin levels in patients with abdominal aortic aneurysm

Inflammation is associated with the disruption of the aortic media and appears to play a fundamental role in the progression and development of abdominal aortic aneurysm (AAA). Haptoglobin (Hp) is a genetically determined acute phase protein, the synthesis of which is increased during inflammation. This study was designed to investigate both phenotype and plasma levels of Hp in patients with AAA.

Patients with documented AAA who were admitted for elective open repair operation or endograft stent implantation, and non-AAA subjects admitted for coronary arteriography, but found to have normal or insignificant coronary artery disease, were included in the study. Plasma Hp levels were determined using a standard specific enzyme-linked immunosorbent assay, while Hp phenotype was determined by native polyacrylamide gel electrophoresis. Total cholesterol, high density lipoprotein, low density lipoprotein, and triglyceride levels were analyzed enzymatically, and C-reactive protein was analyzed by immunochemistry.

Forty-five patients with AAA and 49 non-AAA subjects were included. The Hp 2-2 phenotype was more predominant in AAA patients compared with non-AAA subjects, but this difference was not significant (67% vs 47%; P = .141), while plasma Hp concentrations were significantly higher in AAA patients (237 ± 144 vs 163 ± 86 ng/mL; P = .024). Further analysis revealed that plasma Hp concentrations were significantly higher in AAA patients with the 2-2 phenotype compared with corresponding non-AAA subjects (238 ± 144 vs 163 ± 86 ng/mL;P = .024).

Our findings suggest that plasma Hp concentrations are elevated in patients with AAA, particularly those with the Hp 2-2 phenotype.