CELL-SURFACE RECEPTOR MODULATION ON MONOCYTES AND GRANULOCYTES DURINGCLINICAL AND EXPERIMENTAL HEMODIALYSIS

We studied the modulation of cell surface receptors related to cell ad hesion (L-selectin and Mac-1) on monocytes and granulocytes during cli nical (7 patients treated with cuprophan, Cu, and polysulfone, PS, mem branes, n = 14) and experimental Cu and PS hemodialysis (n = 14). The objective was to compare cell surface receptor modulation in vivo when large subpopulations of cells are withdrawn from the circulating pool with the experimental model when cells are not sequestrated. The expr ession of Mac-1 and L-selectin on monocytes increased during clinical Cu dialysis (p = 0.024 and p = 0.0096, respectively) but remained stab le during PS dialysis. On granulocytes, an inverse receptor modulation of Mac-1 and L-selectin was observed during clinical Cu dialysis but not during PS dialysis. Mac-1 was significantly higher and L-selectin lower on granulocytes after 15 min of clinical Cu as compared to PS di alysis (p = 0.001 and p = 0.0093, respectively). During experimental C u dialysis, Mac-1 expression increased and L-selectin decreased marked ly and continuously on both monocytes and granulocytes. The L selectin /Mac-1 ratio on monocytes and granulocytes may be used as an index of the ability of leukocytes to adhere and to be recruited to an inflamma tory focus. This ratio was significantly lower during clinical Cu as c ompared to PS dialysis (p = 0.0008 and p = 0.0015, respectively) indic ating that the recruitment of leukocytes to infection foci may be prec luded in patients on Cu membranes. Both monocytes and granulocytes sho wed significantly Lower L-selectin/Mac-1 ratio during and after experi mental Cu as compared to PS dialysis. Altered adhesion molecule phenot ype on inflammatory cells during hemodialysis may influence the suscep tibility to infections. Increased shedding of L-selectin in parallel w ith upregulation of Mac-1 may play an important role. Experimental hem odialysis provides information on the mechanisms involved in this proc ess.