Circulating Concentrations of Soluble Interleukin 6 Receptors gp80 and gp130 in Chronic Renal Failure and Effects ofRenal Replacement Therapy

<i>Background:</i> Circulating receptors modulate the biological effects of cytokines. Renal insufficiency is known to influence the concentrations of the soluble tumor necrosis factor (TNF) receptors p55 and p75. No data are available on the concentrations of the circulating interleukin 6 (IL-6) receptors gp80 and gp130 during chronic renal insufficiency. <i>Methods:</i> We compared the serum concentrations of the IL-6 receptors gp80 and gp130 to those of the TNF receptors p55 and p75 in end-stage chronic renal failure, continuous ambulatory peritoneal dialysis, and hemodialysis (HD). <i>Results:</i> In healthy controls the concentrations of gp80, gp130, p55, and p75 in serum were 82.1 ± 24.3, 87.9 ± 20.2, 1.1 ± 0.2, and 1.7 ± 0.3 ng/ml, respectively. These concentrations were increased to, respectively, 112.2 ± 18.0, 186.0 ± 37.7, 10.5 ± 4.3, and 15.0 ± 7.5 ng/ml in chronic renal failure, to 138.8 ± 18.0, 181.3 ± 46.1, 25.5 ± 5.2, and 19.1 ± 3.4 ng/ml in continuous ambulatory peritoneal dialysis, and to 107.9 ± 29.4, 146.6 ± 30.5, 22.9 ± 6.3, and 16.8 ± 6.0 ng/ ml in HD (before dialysis session). The concentrations after HD were higher for p75 only. <i>Conclusions:</i> The data show that the concentrations of the IL-6 receptors (gp80 and gp130) are elevated in chronic renal insufficiency. The increase is relatively low as compared with the elevation of the TNF receptors in this situation. HD does not result in a consistent change in serum concentrations of the various receptors.