Interleukin 6 production of uremic hemodialysed patients: effects of different membranes.

Interleukin-6 (Il-6) has a complex spectrum of biological activities (growth and differentiation of B cells and synthesis of acute-phase proteins by liver). To evaluate the role of this cytokine in the inflammatory response induced by blood interaction with haemodialysis membranes, we have investigated Il-6 synthesis and release in supernatant of 24-h cultured peripheral blood mononuclear cells (PBMC) isolated from ten haemodialysed patients and eight healthy control subjects. In haemodialysed patients, blood samples were drawn before and after their usual dialytic treatment with cuprophane membranes and following 1 and 2 months with polymethylmethacrylate (PMMA) membranes. Il-6 was determined by 72-h incubation of serial dilutions of PBMC supernatant with Il-6-dependent cell line 7TD1; dilutions of rIl-6 were included as standard. Compared to Il-6 synthesis in control subjects (3.3 +/- 2.8 U/ml) the patients usually haemodialysed with cuprophane membranes showed significantly greater values (9.8 +/- 4.5 U/ml, P less than 0.02 before the treatment, and 10.4 +/- 6.1 U/ml, P less than 0.05 after the treatment). A significant reduction, in comparison with the values obtained with cuprophane membranes, was obtained after 1 month (5.3 +/- 2 U/ml, P less than 0.02 before the treatment, and 7.5 +/- 6 U/ml after the treatment) and especially after 2 months (3.4 +/- 3.2 U/ml, P less than 0.02 before the treatment, and 4.4 +/- 3.4 U/ml, P less than 0.05 after the treatment) of dialysis with PMMA membranes. In conclusion, our results show increased Il-6 production in haemodialysed patients usually treated with cuprophane membranes, suggesting a chronic stimulation