Studies of biocompatibility of different dialyzer membranes: role of complement system, intracellular calcium and inositol-triphosphate

Abstract

PMNLs are activated during extracorporeal circulation. The aim of this cross-over biocompatibility study was to investigate the role of complement system, intracellular calcium [Ca2+]i and inositol-triphosphate (IP3) on PMNL degranulation during hemodialysis (HD) with following membranes: polyamide, hemophane and cuprophane. In a second study the effect of complement system, intracellular calcium and IP3 on lactoferrin release during HD with polysulfone and polymethylmethacrylate (PMMA) was also investigated. HD with cuprophane leads to the highest formation of terminal complement component (TCC) followed by PMMA and hemophane. There was a strong correlation between maximal arterial TCC formation and procentual increase of plasma lactoferrin during hemodialysis treatment with all membranes. Both HD with PMMA and hemophane leads to a significant increase of resting [Ca2+]i after 30 minutes of HD. Lowest TCC formation and lowest rise in [Ca2+]i were observed with polysulfone and polyamide. Procentual and absolute increase of [Ca2+]i did also correlate with maximal TCC formation during HD using PMMA, hemophane, polyamide and polysulfone. Since cuprophane induces an initial drop of PMNLs, these cells could not be isolated during HD with cuprophane membranes. Resting PMNL IP3 values were similar before and 30 minutes after begin of hemodialysis and comparable with all membranes used. These data indicate that TCC and intracellular calcium are important signals for PMNL degranulation during HD with cuprophane, PMMA and hemophane. However, mild degranulation of specific PMNL granules can also occur in the absence of significant change in TCC, [Ca2+]i or IP3 levels during HD with polyamide or polysulfone.