ADHERENCE OF HUMAN MONOCYTES TO HEMODIALYSIS MEMBRANES

In the present study we evaluated spontaneous and stimulated adherence of human monocytes to regenerated cellulose and polyacrylonitrile (AN 69) membranes. Spontaneous adherence at 60 min was significantly highe r for regenerated cellulose (28 +/- 2%, P < 0.001) than for AN69 (11 /- 2) membranes. Stimuli such as bacterial lipopolysaccharide, TNFalph a, interleukin-1 and -6 as well as platelet-activating factor, but not IL-4, significantly enhanced adherence at 60 min to AN69 (28 to 30%). In contrast, adherence was not further inducible in the presence of r egenerated cellulose. Both spontaneous and cytokine/bacterial lipopoly saccharide-stimulated adherence were significantly reduced by SDZ-6307 2, a specific platelet-activating factor receptor antagonist. This dif ference in sensitivity of monocyte adherence reflects probably the int rinsic ability of regenerated cellulose to provide maximal spontaneous monocyte adhesion. These data suggest that PAF may act as an adherenc e mediator. This is in line with the ability of regenerated cellulose to directly stimulate monocytes to synthesize platelet-activating fact or and with the ability of cytokines and bacterial lipopolysaccharide to stimulate its synthesis. Although AN69 has a low adherence potentia l, bacterial lipopolysaccharide or cytokines may blunt the biocompatib ility of this membrane.