Serum and urine IL-6 and TNF-alpha in renal transplant recipients with graft dysfunction.

The object of the study presented here was to test whether measurement of blood or urine IL-6 or TNF-alpha could discriminate between the most common causes of renal allograft dysfunction, thus avoiding a biopsy. We present data here in which serum and urine IL-6 and TNF-alpha levels were measured at the same time as a diagnostic renal biopsy was performed. TNF-alpha and IL-6 were measured by sandwich ELISA. Thirty patients had acute cellular rejection, 18 had acute tubular necrosis/CsA toxicity, and 9 had chronic vascular rejection. There was no difference in the levels of IL-6 measured in serum and urine among the three categories of graft dysfunction (t < 1.31; P > 0.20). A similar result with considerable overlap between the groups was seen with TNF-alpha (t < 0.78; P > 0.44). Stratifying the results according to the precise immunosuppressive therapy, CsA dose, body weight, CsA level, body temperature, serum creatinine, the number of previous rejection episodes, original cause of renal failure, or the time elapsed since the transplant did not alter the results. The ratio of serum IL-6 divided by trough CsA level was compared among the three groups and there was no significant difference among them (t < 1.79; P > 0.09). In the light of our results, we therefore suggest that previously published reports of the clinical value of serum and or urine IL-6 and or TNF-alpha in relatively small numbers of patients, not all of whom had been biopsied and in whom rigorous clinical and statistical criteria had not been met, should be viewed with caution.