Antibodies against N-homocysteinylated proteins and their determinants in patients on long-term hemodialysis

INTRODUCTION The factors that determine the level of antibodies against N-homocysteinylated (N-Hcy) proteins have not been established so far. The clinical significance of these antibodies and their effect on cardiovascular (CV) risk in patients with end-stage renal disease (ESRD) are still unknown. OBJECTIVES The aim of this study was to identify the factors that determine the level of antibodies against N-Hcy albumin and N-Hcy hemoglobin in patients on long-term hemodialysis (HD). PATIENTS AND METHODS The study involved 247 subjects on long-term HD (110 women, 137 men; age range, 23-89 years) and 60 controls matched for age, sex, and CV risk factors (serum creatinine level < 140 mu mol/l). Serum antibodies against N-Hcy albumin and N-Hcy hemoglobin were determined using an in-house enzyme-linked immunosorbent assay. Total homocysteine (tHcy), folate, and 8-isoprostaglandin F-2 alpha (8-iso-PGF(2 alpha)) were also measured. RESULTS Patients on HD had higher serum levels of anti-N-Hcy-albumin (absorbancy at 490 nm: 0.56 [0.49-0.623] vs. 0.259 [0.198-0.338], P < 0.0001) and anti-N-Hcy-hemoglobin antibodies (0.659 [0.597-0.723] vs. 0.379 [0.289-0.442], P < 0.0001) as compared with controls. The level of both antibodies correlated with tHcy (r = 0.56, P < 0.0001 and r = 0.67, P < 0.0001, respectively), 8-iso-PGF(2 alpha) (r = 0.48, P < 0.0001 and r = 0.63, P < 0.0001, respectively), and folate (r = -0.18, P = 0.0054 and r = - 0.38, P < 0.0001, respectively), but not with HD duration, the initial cause of ESRD, and CV comorbidity. CONCLUSIONS In HD patients, tHcy is an independent predictor of antibodies against N-Hcy proteins. Folate and 8-iso-PGF(2 alpha) concentrations were not independently associated with the levels of both antibodies.