Activation of human neutrophils after contact with cellulose-based haemodialysis membranes: intracellular calcium signalling in single cells

PURPOSE OF STUDY.: In vitro contact of human leukocytes with cellulose-based dialysismembranes under complement-independent conditions results inactivation of various leukocyte functions. To analyse signalsinvolved in the mechanism of cell activation, we measured changesin cytosolic free calcium ([Ca²⁺]_i) in individual human bloodneutrophils (PMN) upon contact with flat sheet haemodialysismembranes. RESULTS.: By confocal laser-scanning microscopy (CLSM), changes in [Ca²⁺]_iwere monitored in Fluo-3-labelled cells up to 10 min after contactwith a regenerated cellulose (RC) membrane. Multiple [Ca²⁺]_itransients were observed for cells in contact with RC; biostochasticanalysis showed that up to 67% of the PMN responded with a highincrease in [Ca²⁺]_i the rest were low- or non-responding cells.After contact with the new synthetic polycarbonate-polyether(PC-PE) membrane only non-responding cells were seen, indicatingreduced cellular contact activation. The increase in [Ca²⁺]_iof cells on RC could be inhibited by 5 mM L-fucose. This monosaccharidewas recently found to bepresent in cellulose-based polymersin picomolar concentrations. CONCLUSIONS.: The data supports the hypothesis that dialysis-membrane-associatedL-fucose residues participate in complement-independent leukocyteactivation during haemodialysis therapy.