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 monocyte s and granulocytes, sICAM-1 concentrations and the responsiveness of c ells to exogenous fMLP in patients in the intra- (0-4 h Cuprophan dial ysis) and interdialytic period (5-28 h) and in healthy subjects (0-24 h). The high CD11b/CD18, low CD62L granulocyte phenotype occurred rapi dly 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/(CD1 1b/CD18) ratio was reduced up to 12 h after start of treatment on both monocytes and granulocytes. This ratio was significantly lower than i n healthy subjects up to 8 h after start of treatment. The responsiven ess of granulocytes to exogenous fMLP, in terms of CD11b/CD18 mobiliza tion, was significantly reduced in patients during and after hemodialy sis as compared to that on granulocytes obtained from healthy controls . Monocytes were more refractory to fMLP up to 4 h after dialysis. sIC AM-1 was significantly increased in patients before dialysis as compar ed to controls and remained elevated and fairly stable throughout trea tment and in the interdialytic period. The variation in the expression of adhesion molecules on monocytes and on granulocytes in the interdi alytic period was not related to the presence of activating serum fact ors remaining in the circulation after treatment. Our findings emphasi ze the importance of including the interdialytic period in the evaluat ion of dialysis membrane biocompatibility, especially when effects on monocytes are of interest.