Cellulose membranes--time for a change?

Influence of Membranes on Generation of β2 M and Release of Leukocyte Lysosomal Enzymes

Normal leukocyte functional capacity was investigated by evaluation of phagocytosis of opsonised yeast cells in a radiometric test system. After incubation with dialysis membranes (different cellulosic membranes, polysulfon membrane (PS), polymethylmetacrylate membrane (PMMN), the phagocytosis index, expressed as percent decrease with respect to initial values without membrane, decreased by 10%–25%. The most pronounced effect was observed with PS, cuprophane, modified cellulose and PMMA. The results are not related to differences in the viability of PMN during the test procedure; dead PMN amounted to about 4–6.5%. A significant increase in β-NAG and β-Gluc activities was released in the supernatants of the phagocytosis suspensions. This increase activity can be explained by the phagocytosis of PMN but it was not influenced by membrane contact. There was no influence of membrane contact or phagocytosis activity of PMN on the β2M concentration in the supernatant demonstrating that no in vitro generation during incubation with either membrane exists.

Induction of tumour necrosis factor-alpha during haemodialysis. Influence of the membrane type

Some of the secondary clinical effects induced by long-term haemodialysis in patients with end-stage renal failure have been related to an increased production of interleukin-1 (IL-1). We investigated the role of another cytokine which shares a number of biological properties with IL-1, tumour necrosis factor-alpha (TNF-alpha). In long-term haemodialysed patients, we found at the beginning of the dialysis increased plasma TNF-alpha levels and enhanced monocyte capacity to produce TNF-alpha spontaneously ex vivo. Non-haemodialysed uraemic patients also presented increased plasma TNF-alpha levels. During dialysis with cellulose acetate (CA) or polysulphone (PS) membranes, plasma TNF-alpha levels and the spontaneous and lipopolysaccharide-induced production of TNF-alpha by monocytes remained at predialysis levels. In contrast, when cuprophane membranes were used, there was a significant increase in plasma TNF-alpha levels and in both spontaneous (10-fold) and lipopolysaccharide-induced (seven-fold) ex vivo TNF-alpha production by monocytes. These results suggest that monocytes are stimulated during haemodialysis with the poorly biocompatible cuprophane membrane.

Activation of the complement system at the interface between blood and artificial surfaces

The interaction between blood and the artificial devices used in haemodialysis results in the activation of the immune system. Complement activation is known to play a key role in the production of inflammatory mediators. This article describes the complement system and the way in which it is triggered in the patient undergoing haemodialysis. It highlights those factors thought to be of particular importance in the pathogenesis of adverse reactions and targets them as obstacles to be overcome in the future design of biocompatible materials.

Role of proteases in patients with acute renal failure and regular hemodialysis therapy

The potential role of proteases in patients with acute renal failure and regular hemodialysis therapy was investigated. Proteases released from blood cells, damaged kidney cortex and different strains of Pseudomonas aeruginosa in patients with septicemia may contribute to an accelerated protein catabolism. The imbalance of the protease-antiprotease system suggests the valve of active antiproteolytic agents in the treatment of these pathologic states. Our own observation of an in vitro suppression of enhanced proteolysis by the administration of alpha 2-macroglobulin seems to support the usefulness of such a procedure (W.H. Hörl, C. Gautert, I.O. Auer et al., Am. J. Nephrol., 2 (1982) 32-35). As long as alpha 2-macroglobulin is not available, the value of its treatment has to be confirmed by the administration of fresh frozen plasma containing alpha 2-macroglobulin. Also the search for other active antiproteolytic agents is required.