ACTIVATION OF HUMAN NEUTROPHILS AFTER CONTACT WITH CELLULOSE-BASED HEMODIALYSIS MEMBRANES - INTRACELLULAR CALCIUM SIGNALING IN SINGLE CELLS

Purpose of study. In vitro contact of human leukocytes with cellulose- based dialysis membranes under complement-independent conditions resul ts in activation of various leukocyte functions. To analyse signals in volved in the mechanism of cell activation, we measured changes in cyt osolic free calcium ([Ca2(+)](i)) in individual human blood neutrophil s (PMN) upon contact with flat sheet haemodialysis membranes. Results. By confocal laser-scanning microscopy (CLSM), changes in [Ca2+](i) we re monitored in Fluo-3-labelled cells up to 10 min after contact with a regenerated cellulose (RC) membrane. Multiple [Ca2+](i) transients w ere observed for cells in contact with RC; biostochastic analysis show ed that up to 67% of the PMN responded with a high increase in [Ca2+]( i), the rest were low- or non-responding cells. After contact with the new synthetic polycarbonate-polyether (PC-PE) membrane only non-respo nding cells were seen, indicating reduced cellular contact activation. The increase in [Ca2+](i) of cells on RC could be inhibited by 5 mM L -fucose. This monosaccharide was recently found to bepresent in cellul ose-based polymers in picomolar concentrations. Conclusions. The data supports the hypothesis that dialysis-membrane-associated L-fucose res idues participate in complement-independent leukocyte activation durin g haemodialysis therapy.