Non-endotoxinic tumour necrosis factor-alpha-inducing factors in haemodialysis

A transmembrane passage of endotoxins may account for the dysfunction of cytokine production which has been often reported in haemodialysis. We developed an assay based on the ability of patient serum to stimulate tumour necrosis factor alpha (TNF alpha) secretion in normal peripheral blood mononuclear cells. Three groups of subjects were investigated: normal controls (n = 14), patients with chronic renal failure, CRF (n = 15), and patients dialysed with polyacrylonitrile (n = 7), polysulphone (n = 8), and cellulose acetate (n = 7). Sera from dialysed patients displayed a significantly higher TNF alpha-inducing activity than those of controls and CRF patients. The ability of serum to elicit TNF alpha secretion was neither modified during the dialysis session nor influenced by the type of haemodialysis membrane. TNF alpha-inducing activity in serum was not inhibited by polymyxin B, known to impair endotoxin-dependent cell responses, thus suggesting that it was not related to circulating endotoxins. We conclude that non-endotoxinic factors are present in serum from dialysed patients and are able to induce cytokine secretion.