Involvement of peripheral blood monocytes in haemodialysis: in vivo induction of tumour necrosis factor alpha, interleukin 6 and beta 2-microglobulin

Abstract

Our aim was to evaluate the role of three different variables in the activation of the monocyte system: dialysis membrane (cuprophane or polyacrylonitrile), dialysate (acetate or bicarbonate), and procedure (standard or high-flux haemodialysis). By ELISA test we measured the 'in vivo' intracellular (monocyte-associated) production and extracellular release of tumour necrosis factor alpha (TNF alpha), interleukin-6 (Il-6) and beta 2-microglobulin (beta 2-M) by monocytes from 20 uraemic patients before and after the dialysis session. At the beginning of the dialysis session, uraemic patients' cultured monocytes spontaneously released a greater amount of TNF alpha, Il-6 and beta 2-M compared to normal controls. However, no differences in cytokine and beta 2-M were observed in monocyte lysate between the two groups. At the end of the dialysis session, cultured monocytes from patients treated with cellulosic membranes and acetate dialysate showed greater TNF alpha values than normal controls (P less than 0.001 and P less than 0.05 respectively). Moreover, TNF alpha and Il-6 values were strictly correlated (P less than 0.05). These results clearly show an activation of the monocyte system in uraemic patients undergoing periodic haemodialysis. The implicated factors may be multiple, such as complement activating cellulosic membranes or acetate dialysate. The production of TNF alpha, Il-6 and beta 2-M may explain some of the pathological findings observed in long-term haemodialysis patients.