CELL-ASSOCIATED ADHESION MOLECULES AS EARLY MARKERS OF BIOINCOMPATIBILITY

Background, Transient nature of adhesive interactions occurring during cell margination is mainly dependent on expression of selectins which are shed by activated cells. This shedding in the circulation may pla y an important role as anti-inflammatory mediator. Haemodialysis is al so associated with P-selectin (CD62P)/sialyl-Lewisx (CD15s) interactio ns which mediate platelet-leukocyte coaggregation, We further investig ated the mechanisms underlying leukocyte margination during haemodialy sis. Methods. CD15s, CD11b and CD61 expression on circulating leukocyt es from patients dialysed on synthetic membranes (modified polyacrylon itrile (SPAN), polysulphone (PS), and polyacrylonitrile (AN69) was ass essed by cytofluorometry in a prospective crossover trial. We measured plasma levels C3a/C3a desArg, soluble CD62P, and CD62E molecules obta ined from patients and healthy individuals. Results. Expression of CD1 1b and CD15s was upregulated on neutrophils from patients dialysed wit h SPAN and PS membranes during the dialysis session. A significant neg ative correlation was found between the expression of CD11b or CD15s m olecules and neutrophil counts as well as between CD15s expression and monocyte counts during haemodialysis. As assessed by CD61 expression on leukocytes, we observed that platelets bound significantly onto bot h neutrophils and monocytes during dialysis with both membranes. A sig nificant positive correlation was found between the expression of CD11 b molecules and the percentage of CD61+ monocytes counts during SPAN a nd PS dialysis. Wi found a significant increase of soluble CD62P in pl asma samples obtained from haemodialysed patients before the dialysis session as compared to the levels detected in plasma from healthy indi viduals. Conclusions, This study documents a major role of CD15s, CD11 b, CD61, CD62P molecules in the transient leukocytes activation and ma rgination during haemodialysis on synthetic membranes despite their lo w complement-activating properties.