CITRATE ANTICOAGULATION DOES NOT CORRECT CUPROPHANE BIOINCOMPATIBILITY AS EVALUATED BY THE EXPRESSION OF LEUKOCYTE SURFACE MOLECULES

Background. Citrate, used for the anticoagulation of the extracorporea l dialysis circuit, reduces ionized calcium by chelation and has been claimed to attenuate dialyser membrane bioincompatibility. Dialysis wi th complement-activating cuprophane membranes is associated with leuko penia which has been related to an increase in adhesion molecule expre ssion on the surface of circulating leukocytes. Methods. The effect of citrate anticoagulation on the expression of CD11b, CD11c and CD45 on the surf;ice of granulocytes and CD14 on monocytes during haemodialys is with cuprophane membranes, was evaluated by flow cytometric analysi s. A comparison of standard heparin vs citrate was performed in 14 chr onic haemodialysis patients. During citrate anticoagulation a calcium- free dialysate was used and citrate was infused to obtain a concentrat ion of 4.3 mmol/l blood. The unchallenged 'baseline state' expression of the surface molecules and the increase after ex vivo stimulation wi th phorbol 12-myristate 13-acetate (delta-PMA) or formyl-methionyl-leu cyl-phenylalanine (delta-fMLP) was studied. Results, With heparin, as well as with citrate, a sharp fall in granulocyle and monocyte count w as observed after 15 min of dialysis, followed by a recovery at the en d of the session. The expression of CD11b, CD11c and CD45 on granulocy tes increased markedly during cuprophane dialysis with a peak at 15 mi n; there were no differences in response between heparin and citrate a nticoagulation. Delta-PMA and delta-fMLP for CD45, CD11c and CD14 show ed a decrease during cuprophane dialysis vs t(0); again there were no differences between heparin and citrate. Conclusion. We conclude that the use of citrate was not associated with reduced leukocyte activatio n as measured by the expression of surface molecules during cuprophane dialysis and that no effect on dialysis leukocytopenia could be regis tered.