POLY(ETHYLENEIMINE) MODIFIED FILTERS FOR THE REMOVAL OF LEUKOCYTES FROM BLOOD

Polyurethane membrane filters and filters coated with poly(ethyleneimi ne) were used to investigate the influence of leukocyte adhesion durin g filtration. Treatment of the filters with an aqueous solution of 1% (w/v) poly(ethyleneimine) (PEI) led to the introduction of amine group s at the filter surfaces, as was confirmed by X-ray photoelectron spec troscopy. The modification procedure did not significantly change the porous structure in the filters, as was demonstrated by SEM and porome try. Using C-14-labeled poly(ethyleneimine) it was shown that nearly a complete coverage (approximately 0.1 mg/m2) was achieved that did not desorb from the filter surface during contact with blood plasma. When the filtration was carried out with purified leukocytes in the absenc e of red cells, platelets, and blood plasma, the number of cells remov ed by modified filters (>95%) was significantly higher as compared to the removal with unmodified filters (approximately 80%). However, no s ignificant differences between the filters were found when the filtrat ion was performed with whole blood. This finding was unexpected, becau se it was shown before that immobilization of poly(ethyleneimine) on s olid polyurethane film, surfaces promoted the adhesion of leukocytes f rom whole blood. Apparently, the adhesive properties of the PEI dimini sh during filtration. Filter coating of commercial leukocyte filters c omposed of polyester fibers also had no effect on the removal of leuko cytes from whole blood. It was postulated that morphological factors, such as filter shape, roughness, tortuosity, and porosity rather than the physicochemical properties of the filter surface influence cell ad hesion to the filter surface, and through that the filtration process. (C) 1993 John Wiley & Sons, Inc.