GRANULOCYTE SEQUESTRATION IN DIALYZERS - A COMPARATIVE ELUTION STUDY OF 3 DIFFERENT MEMBRANES

Background. The present study was designed to investigate the expressi on of activation markers on polymorphonuclear cells (PMN) in periphera l blood and dialyser eluates, comparing three different membranes. Met hods. Eight patients were studied during HD with cellulose triacetate (CTA), cuprammonium (CU), and polysulphone (PS) dialysers in a randomi zed crossover design. In addition to total cell count and microscopic leukocyte differentiation, the expression of degranulation (CD63, CD66 b) and adhesion (CD62L) markers on PMN was analysed in peripheral bloo d over time, and in dialyser eluates at the end of HD. Results. In per ipheral blood a significant drop in PMN was noted only during CU KD (P < 0.001), whereas none of the membranes induced any substantial chang e in the expression of the activation markers mentioned. In dialyser e luates the mean number of cells was 53 x 10(6), CTA yielding a signifi cantly higher number as compared with CU (P = 0.05). The proportion of PMN was 81-91% (P < 0.05 versus peripheral blood). The expression of CD63, and especially CD66b, in dialyser eluates of all membranes was s ignificantly higher in comparison with peripheral blood, whereas the e xpression of CD62L in dialyser eluates was considerably lower. Conclus ions. Dialyser eluates of all three dialysers consisted mainly of PMN. Based on the relatively modest cell numbers and the expression of the activation markers described, our results suggest primarily degranula tion within the dialyser. Apart from differences in cell numbers, CTA yielding the highest cell counts, no differences between CTA, CU, and PS could be demonstrated in dialyser eluates.