Generation and removal of anaphylatoxins during hemofiltration with five different membranes

The generation of anaphylatoxins (C3a and C5a) during hemofiltration with polysulfone (F60), acrylonitrile (AN69 HF), polyamid (FH77), polyacrylonitrile (PAN200) and cellulose-acetate (Duo-Flux) membranes were investigated. The 'net' production of C3a in the blood compartment during the treatment was 3,028 micrograms (Duo-Flux), 1,845 micrograms (FH77), 270 micrograms (F60), -2,388 micrograms (AN69 HF) and -5,189 micrograms (PAN200), the latter two negative values reflecting a high adsorption of C3a to the membrane material. Corresponding values for C5a were 185 micrograms (AN69 HF), 108 micrograms (F60), 83 micrograms (PAN200), 6 micrograms (FH77) and -133 micrograms (Duo-Flux). The sieving coefficient remained stable for C5a throughout the treatment, while it fell significantly for C3a with the F60 membrane (0.44-0.25) and increased significantly for the FH77 membrane (0.14-0.33). The cellulose-acetate membrane device produced the most pronounced drop in white blood cell counts and the acrylonitrile membrane the least. The Duo-Flux device was significantly less biocompatible than the other membranes investigated, while little differences were found between AN69 HF, F60, FH77 and PAN200. When hemodialysis is compared with hemofiltration employing the same membranes, the latter appears to be a more biocompatible treatment modality partly due to convective removal of activated complement from the blood compartment into the filtrate.