Biocompatibility of different hemodialysis membranes: activation of complement and leukopenia.

The ability of three hollow-fiber dialyzers (Cuprophane [CU], polymethylmethacrylate [PMMA], and polyacrylonitrile [PAN]) to activate complement and to induce leukopenia was studied prospectively in six patients on long-term hemodialysis. CU membranes caused the most intense complement activation with C3a, C3d, and C5a levels peaking 15 min after beginning dialysis. Total white blood cell (WBC) counts dropped simultaneously by 76%, and the decrease in leukocytes was inversely correlated with the levels of C3a and C5a. In contrast, PMMA membranes led only to slight complement activation with an associated fall in WBC counts of 29%, and PAN membranes induced very little complement activation without leukopenia. In vitro studies involving incubation of normal human plasma with each of the three membranes corroborated these findings. The results suggest that the biocompatibility of PMMA and PAN dialyzers is superior to CU.