Can Uremia and Hemodialysis Affect Plasma Levels of Circulating TNF-alpha

It is well known that uremia is associated with increased susceptibility to infection. In addition, patients on haemodialysis (HD) experience a variety of dialysis associated complications, both acute and chronic, many of them having features similar to acute phase response. Immunoregulatory cytokines such as tumor necrosis factor-a (TNF-a) have been implicated in the pathogenesis of immunological as well as inflammatory diseases. Thus, TNF-a levels could be expected to be high in uremic patients as well as in HD patients. We investigated the plasma levels of TNF-a in 17 patients with renal failure, seven patients with chronic renal failure (CRF) before commencement of HD and 10 patients maintained on regular HD. Eight age matched healthy subjects were studied as normal control. All CRF patients, who were not yet on dialysis, had high plasma levels of TNF-a (mean + SD 71.33 + 33.25 pg/ml). Out of the HD group, TNF-a plasma levels were not detectable in five patients and in the remaining five, TNF-a plasma level (mean + SD 21.06 + 7.72) were comparable to the normal controls (mean + SD 21 + 7.87). Our findings suggest that factors related to uremia, but not to HD, are responsible for high TNF-a plasma levels in these patients and that, HD probably has a beneficial effect by removal and/or neutralising of uremic toxins.