Polyacrylonitrile membranes in hemodialysis: blood-surface interactions

Investigations of blood-surface interaction phenomena with polyacrylonitrile-based membrane (AN-69) during hemodialysis are reported. The amount and surface distribution of adhering white blood cells (WBC), and adsorbed proteins (Pt) have been evaluated by image analysis of WBC, spectrophotometry and SDS-polyacrylamide gel electrophoresis of desorbed proteins. The protein contents of the patient's serum have been also investigated by SDS-electrophoresis. Results indicate that the distribution of both WBC, and Pt is non-uniform, and higher (71%, and 79% of the total detected amount, respectively) in the half membrane near the blood inlet (PAN-IN); PAN-IN and PAN-OUT eluates show the same protein bands by electrophoresis. The concentration of the proteins stably adsorbed on the membranes appears not to be related to their concentration in the patient's serum. A relatively strong band at MW = 14,400 in PAN eluates could be interpreted as the presence of lysozyme bound to the AN-69 membranes.