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

Abstract

In vitro contact of human leukocytes with cellulose-based dialysis membranes under complement-independent conditions results in activation of various leukocyte functions. To analyse signals involved in the mechanism of cell activation, we measured changes in cytosolic free calcium ([Ca2+]i) in individual human blood neutrophils (PMN) upon contact with flat sheet haemodialysis membranes. By confocal laser-scanning microscopy (CLSM), changes in [Ca2+]i were monitored in Fluo-3-labelled cells up to 10 min after contact with a regenerated cellulose (RC) membrane. Multiple [Ca2+]i transients were observed for cells in contact with RC; biostochastic analysis showed 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-responding cells were seen, indicating reduced cellular contact activation. The increase in [Ca2+]i of cells on RC could be inhibited by 5mM L-fucose. This monosaccharide was recently found to be present in cellulose-based polymers in picomolar concentrations. The data supports the hypothesis that dialysis-membrane-associated L-fucose residues participate in complement-independent leukocyte activation during haemodialysis therapy.