CUPROPHANE HEMODIALYSIS INDUCES UP-REGULATION OF LPS RECEPTOR (CD14) ON MONOCYTES - ROLE OF COMPLEMENT ACTIVATION

Background. The CD14 molecule is a high-affinity receptor for the comp lex formed by lipopolysaccharide (LPS) and LPS-binding protein. Method s. We examined by flow cytometry the effect of in vitro and in vivo ha emodialysis on cuprophane membrane and recombinant C5a on the expressi on of CD14 molecules at the surface of monocytes. Monocyte CD14 expres sion was also studied during in vitro and in vivo haemodialysis on pol yacrylonitrile AN69 membrane. Results. In vitro haemodialysis of whole blood from healthy volunteers on cuprophane membrane resulted within 30 min in upregulation of monocyte CD14 expression. The reuse of the c uprophane membrane abolished both complement activation and CD14 upreg ulation. Moreover, incubation of whole blood with recombinant C5a led to an increased monocyte CD14 expression supporting a role for complem ent activation in the rapid cuprophane-induced CD14 upregulation. Duri ng AN69 dialysis which is not associated with complement activation in the blood phase, monocyte CD14 expression did not change during the f irst 60 min but was significantly increased after 3 h of in vitro haem odialysis. This late increase might be related to the presence of comp lement activation products adsorbed on the membrane. In vivo dialysis on cuprophane membrane also resulted in early monocyte CD14 upregulati on as indicated by the higher CD14 expression found after 60 min on mo nocytes obtained from the efferent as compared to the afferent line of the dialyser, a phenomenon that was not observed during haemodialysis on AN69 membrane. Conclusion. Haemodialysis on the complement-activat ing cuprophane membrane induces the rapid upregulation of the CD14 LPS -receptor on monocytes.