Biocompatibility of dialysis membranes: a comparative study.

White blood cell counts and plasma C5a anaphylatoxin values were studied during haemodialysis with cuprophane, ethylenevinylalcohol, polycarbonate, polymethylmethacrylate, acrylonitrile, polysulphone and polyacrylonitrile membrane dialysers. Cuprophane induced marked leukopenia with striking plasma generation of C5a. Ethylenevinylalcohol, polycarbonate, polymethylmethacrylate and acrylonitrile promoted an intermediate degree of leukopenia with mild but significant complement activation; however, leukopenia and C5a generation were not time-related with some of these membranes. In contrast, polysulphone and polyacrylonitrile showed neither leukopenia nor C5a increase. These data suggest that although there must be further factors involved, complement-derived anaphylatoxin C5a generation may have a relevant role in the mechanism of haemodialysis-induced leukopenia. At the present time evaluation of the leukopenic effect and the C5a generation capability of a membrane seem worthwhile for estimating its degree of biocompatibility.