Monocyte and granulocyte CD11b/CD18, CD62L expression and sICAM-1 concentration in the interdialytic period

We studied cell surface modulation of CD11b/CD18 and CD62L on monocytes and granulocytes, sICAM-1 concentrations and the responsiveness of cells to exogenous fMLP in patients in the intra- (0-4 h Cuprophan dialysis) and interdialytic period (5-28 h) and in healthy subjects (0-24 h). The high CD11b/CD18, low CD62L granulocyte phenotype occurred rapidly during dialysis. By contrast, CD62L increased on the subpopulation of monocytes in circulation initially during dialysis and CD11b/CD18 was mobilized much slower. In the interdialytic period, the CD62L/(CD11b/CD18) ratio was reduced up to 12 h after start of treatment on both monocytes and granulocytes. This ratio was significantly lower than in healthy subjects up to 8 h after start of treatment. The responsiveness of granulocytes to exogenous fMLP, in terms of CD11b/CD18 mobilization, was significantly reduced in patients during and after hemodialysis as compared to that on granulocytes obtained from healthy controls. Monocytes were more refractory to fMLP up to 4 h after dialysis. sICAM-1 was significantly increased in patients before dialysis as compared to controls and remained elevated and fairly stable throughout treatment and in the interdialytic period. The variation in the expression of adhesion molecules on monocytes and on granulocytes in the interdialytic period was not related to the presence of activating serum factors remaining in the circulation after treatment. Our findings emphasize the importance of including the interdialytic period in the evaluation of dialysis membrane biocompatibility, especially when effects on monocytes are of interest.