Cuprophane haemodialysis induces upregulation of LPS receptor (CD14) on monocytes: role of complement activation.

BACKGROUND

The CD14 molecule is a high-affinity receptor for the complex formed by lipopolysaccharide (LPS) and LPS-binding protein.

METHODS

We examined by flow cytometry the effect of in vitro and in vivo haemodialysis on cuprophane membrane and recombinant C5a on the expression of CD14 molecules at the surface on monocytes. Monocyte CD14 expression was also studied during in vitro and in vivo haemodialysis on polyacrylonitrile 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 cuprophane membrane abolished both complement activation and CD14 upregulation. Moreover, incubation of whole blood with recombinant C5a led to an increased monocyte CD14 expression supporting a role for complement activation in the rapid cuprophane-induced CD14 upregulation. During AN69 dialysis which is not associated with complement activation in the blood phase, monocyte CD14 expression did not change during the first 60 min but was significantly increased after 3 h of in vitro haemodialysis. This late increase might be related to the presence of complement activation products adsorbed on the membrane. In vivo dialysis on cuprophane membrane also resulted in early monocyte CD14 upregulation as indicated by higher CD14 expression found after 60 min on monocytes 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-activating cuprophane membrane induces the rapid upregulation of the CD14 LPS-receptor on monocytes.