Background: The present study was designed to investigate the expression of activation markers on polymorphonuclear cells (PMN) in peripheral blood and dialyser eluates, comparing three different membranes.
Methods: Eight patients were studied during HD with cellulose triacetate (CTA), cuprammonium (CU), and polysulphone (PS) dialysers in a randomized crossover design. In addition to total cell count and microscopic leukocyte differentiation, the expression of degranulation (CD63, CD66b) and adhesion (CD62L) markers on PMN was analysed in peripheral blood over time, and in dialyser eluates at the end of HD.
Results: In peripheral blood a significant drop in PMN was noted only during CU HD (P < 0.001), whereas none of the membranes induced any substantial change in the expression of the activation markers mentioned. In dialyser eluates the mean number of cells was 53 x 10(6), CTA yielding a significantly 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 significantly higher in comparison with peripheral blood, whereas the expression of CD62L in dialyser eluates was considerably lower.
Conclusions: 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 degranulation 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.