IN-VIVO EVALUATION OF PLATELET ACTIVATION BY DIFFERENT CELLULOSIC MEMBRANES

This study was undertaken to evaluate platelet activation in vivo indu ced by different cellulosic membranes by measuring the expression of P -selectin on the platelet surface during hemodialysis in 9 uremic pati ents, Hollow fiber dialyzers of similar surface with different cellulo sic membranes (Cuprophan, cellulose acetate, cellulose triacetate, and Hemophan) were evaluated and compared to a synthetic membrane (polysu lfone). Blood samples were obtained before hemodialysis and from the e fferent and afferent limbs 5 min after the beginning of dialysis. P-se lectin exposure was evaluated by flow cytometry (FACScan) using a mono clonal antibody (RUU 2.17), The percentage of platelets expressing P-s electin before hemodialysis and the percentage from the arterial line during hemodialysis were similar. All membranes evaluated induced plat elet activation (estimated as the increase in percentage of platelets expressing P-selectin in samples obtained from the venous line with re spect to the arterial line). Cuprophan induced more platelet activatio n than any other membrane (p < 0.05). The activation induced by cellul ose acetate and cellulose triacetate membranes was also higher than th at observed with Hemophan (p < 0.05), Hemophan-induced platelet activa tion was similar to that of polysulfone. These results indicate that a ll cellulosic membranes induce platelet activation during hemodialysis although there are quantitative differences among them, While Cuproph an induced the highest degree of platelet activation, Hemophan was the only cellulosic membrane that showed a degree of platelet activation similar to the biocompatible membrane polysulfone.