Different subclasses and isotypes of antibodies against phosphorylcholine in haemodialysis patients: association with mortality.

BACKGROUND: The risk of premature death is high among patients on haemodialysis (HD-patients). We previously determined that IgM antibodies against phosphorylcholine (anti-PC) are negatively associated with increased risk of cardiovascular disease (CVD), atherosclerosis, some autoimmune diseases and with mortality among HD-patients in this cohort. We here study also other subclasses and isotypes of anti-PC in HD-patients, in relation to mortality, inflammation and gender. METHODS: The study group is a cohort of 209 prevalent HD patients (median age 66 (interquartile range (IQR): 51-74]) years, vintage time 29 (IQR 15-58; 56% men) months) with a mean follow-up period of 41 (IQR 20-60 months). Fifty-six % were men. We also divided patients into inflamed (CRP>5.6 mg/ml and non-inflamed. Antibody levels were determined by in-house ELISA. RESULTS: IgG1 anti-PC below median was significantly associated with increased all-cause mortality (after adjustment for confounders: p=0.02) while IgG, IgA and IgG2 anti-PC were not associated with this outcome. Among non-inflamed patients, IgM and IgG1 anti-PC were significantly associated with mortality (p=0.047 and 0.02). IgG1 anti-PC was significantly associated with mortality among men (p=0.03) and trendwise among women (p=0.26). CONCLUSION: IgM (as previously reported) and IgG1 anti-PC are negatively associated with survival among HD-patients and non-inflamed HD-patients, but among inflamed patients there were no associations. IgG, IgA or IgG2 anti-PC were not associated with survival in these groups and subgroups. Further studies are needed to determine if raising anti-PC levels, especially IgM and IgG1 anti-PC, through immunization, is beneficial.