Control of hepatic parameters in renal cell carcinoma (RCC) by interleukin-6 (IL-6)?

RCC can go hand-in-hand with an elevation of various hepatic proteins. An interrelationship between the IL-6 titer, C-reactive protein (CRP) and the blood sedimentation rate (BSR) has already been proven. The aim of the present study was to study 1) the possibility of differentiating between healthy and RCC patients via IL-6 in the serum and 2) the relationship of IL-6 to hepatic parameters {alkaline phosphatase (AP), gamma-glutamyltransferase (gGT), serum proteins (E'p)} and the usual clinical prognostic parameters (tumor grading, staging). Serum analysis of 38 healthy patients via ELISA (DPC-Biermann, Germany) showed normal values of 1.2 ng/ml for IL-6, with a standards deviation of +/- 1.7 and a peak concentration of 3 ng/ml (specificity: 95%). In 20 RCCs there were IL-6 titers of 10.7 ng/ml +/- 6.56 in the pre-operative serum. The sensitivity of IL-6 was about 90%. The difference was statistically significant (p < 0.0001, Wilcoxon test). For IL-6 there was a positive correlation with the BSR (1-hour value: r = 0.7; 2-hour value: r = 0.6), CRP (r = 0.85), E'p (r = 0.6), and gGT (r = 0.6). No correlation was found between AP, the Robson stage, grading, and IL-6. IL-6 is potentially suitable for differentiating between healthy and RCC patients but is not tumor specific. IL-6 has a strong correlation with all laboratory values which were analyzed except AP thus there is considerable evidence for a cytokine (IL-6) control of the hepatic changes. Since some of the above-named laboratory parameters have prognostic relevance, IL-6 can be regarded as a cumulative prognostic parameter.