Activation of FXII during haemodialysis

This study was designed to provide information on the kinetics of FXIIa activity and C3d release during haemodialysis. Dialysis was performed twice in 9 stable patient for 240 min with the same conditions except for a change in dialysate sodium profile (using a linear sodium programme starting at 138 and ending at 148 mmol/l or vice versa). Using paired statistics there was a significant (p < 0.02) increase in both C3d release and the FXIIa activity. The sodium profiles did not alter the outcome. The increase in FXIIa activity, which is maximal at the end of dialysis, is continuous, unlike the C3d release, which is maximal within 15 min of dialysis and then levels off. Both interactions are induced by the blood membrane contact. These results indicate that the FXIIa activation is not strictly coupled to the activation of the complement system.