Is the dialysate fluid source of complement activating factors?

To distinguish between membrane-induced and dialysate-induced mechanism of complement activation attending hemodialysis (HD), the C3a plasma level and blood neutrophil count profiles have been determined during procedures performed with noncellulosic membranes, as PAN and PMMA (with minimal complement-activating potential) and, by comparison, with new cuprophane (that displays the greatest complement-activating potential). Furthermore, PAN and PMMA membranes have been used in 2 other blood purification methods: high efficiency hemofiltration (HEHF), in which there is no dialysate on the other side of the membrane, and hemofiltration without substitution fluid and with reinfusion of dialysis-regenerated hemofiltrate (HWSF), in which the dialysate is separated from the blood circuit by the hemofiltrate circuit. In addition, sequential dialysis-ultrafiltration (UFD) experiments with PAN membranes have been performed, where dialysate was present only in the second part of the procedure. In all the HD and UFD procedures LAL test assays were performed on dialysate at the same times as C3a and neutrophil determinations. Our findings seem to suggest that the dialysate can be a source of complement activating factors; complement activation detectable by C3a plasma levels can ensue when LAL test-positive material is present in the dialysate.