Complement in patients receiving maintenance hemodialysis: functional screening and quantitative analysis

In the present study, 244 HD patients at one dialysis center and 204 healthy controls were enrolled. Functional complement activities were measured simultaneously using the Wielisa？-kit. The combination of the results of these three pathway activities allows us to speculate which candidate complement is deficient; subsequently, the deficient complement was determined.All three functional complement activities were significantly higher in the HD patients than in the control group (P < 0.01 for all cases). After identifying candidates in both groups with complement deficiencies using the Wielisa？-kit, 16 sera (8.8%) with mannose-binding lectin (MBL) deficiency, 1 serum (0.4%) with C4 deficiency, 1 serum (0.4%) with C9 deficiency, and 1 serum (0.4%) with B deficiency were observed in the HD group, and 18 sera (8.8%) with MBL deficiency and 1 serum (0.5%) with B deficiency were observed in the control group. There were no significant differences in the 5-year mortality rate between each complement-deficient group and the complement-sufficient group among the HD patients.This is the first report that profiles complement deficiencies by simultaneous measurement of functional activities of the three complement pathways in HD patients. Hemodialysis patients frequently suffer from infections or malignancies, but functional complement deficiencies do not confer additional risk of mortality.The complement system is part of the innate immune system comprising at least 40 proteins that collaborate in a complex fashion in the removal of microorganisms and apoptotic cells, but also serves as an opsonin, enhancing and directing adaptive immunity [1,2].Complement deficiencies associated with several clinical diseases involving impairment of the immune system have been recognized. For example, various reports suggest that complement deficiencies are highly associated with an increased risk for infectious disease [3,4]. Previous studies proposed that complement deficiencies may be a r