MODULATION OF CD11B CD18 ON MONOCYTES AND GRANULOCYTES FOLLOWING HEMODIALYSIS MEMBRANE INTERACTION IN-VITRO/

We studied the generation of CD11b/CD18 mobilizing factors in serum af ter incubation with dialysis membrane fragments of different chemical composition. We also evaluated the relative importance of the alternat ive and classical pathways of the complement system in the generation of such factors. Monocytes and granulocytes from healthy blood donors were incubated in normal human serum (NHS) and in NHS that had been pr eincubated with Cuprophan (CU) membrane (NHS-CU), Hemophan (HE) (NHS-H E) or polysulfone (PS) (NHS-PS). NHS-CU caused the highest up-regulati on of the CD11b/CD18 receptor on monocytes and granulocytes. The rank in capacity to mobilize CD11b/CD18 on granulocytes was CU>HE>PS (p<0.0 01), CU>HE (p<0.05) and HE>PS (p<0.001). The rank in capacity to mobil ize CD11b/CD18 on monocytes was CU>HE>PS (p<0.001), CU>HE (p<0.05) and HE>PS (p<0.01). NHS-PS induced a lower up-regulation of CD11b/CD18 co mpared to NHS which indicates that serum factors with the ability to m obilize the CD11b/CD18 receptor on monocytes and granulocytes are depo sited on or adsorbed by PS. In order to study the relative contributio n of the alternative and classical pathways of the complement system i n the generation of CD11b/CD18 mobilizing factors in serum, three diff erent serum preparations (1. both pathways intact. 2. only the alterna tive intact and 3. only the classical pathway intact) were used. The C U membrane activated the classical pathway to a larger extent than the PS membrane (p<0.01). When only the alternative pathway was intact no difference in the generation of CD11b/CD18 mobilizing factors between the CU and PS membranes was observed. These studies show that CD11b/C D18 mobilizing serum factors are generated after incubation with GU me mbranes and that such factors are probably adsorbed by PS. The classic al pathway of complement activation seems to contribute to the generat ion of CD11b/CD18 mobilizing factors in serum.