Interleukin-6 localization and the prognosis of IgA nephropathy

Various cytokines and growth factors may be involved in IgA nephropathy. To clarify whether interleukin-6 was a prognostic factor for this disease, we investigated interleukin-6 positivity of renal biopsy specimens and its re lationship with the prognosis. The subjects were 90 patients with IgA nephr opathy (42 males and 48 females with a median age of 32.7 +/- 13.8 years). Renal biopsy specimens were stained for interleukin-6 using an enzyme-antib ody method. Fifty-two of 90 patients showed glomerular positivity for inter leukin-6. Among the patients positive for interleukin-6, 24-hour urinary pr otein excretion and serum creatinine levels were significantly higher at th e time of biopsy than in the patients without interleukin-6 positivity, whi le creatinine clearance was significantly lower. In the interleukin-6-posit ive patients without steroid therapy, serum creatinine increased significan tly after 1 year (Delta s-Cr; 1.04 +/- 0.45 mg/dl) and creatinine clearance decreased significantly (Delta Ccr; -11.7 +/- 3.2 ml/min) compared to the interleukin-6-negative patients without steroid therapy. Steroid therapy im proved 24-hour urinary protein excretion, serum creatinine, and creatinine clearance in the interleukin-6-positive patients, while these parameters wo rsened without steroid therapy. On the other hand, the IL-6-negative patien ts showed no differences of clinical parameters irrespective of the presenc e or absence of steroid therapy. In conclusion, glomerular interleukin-6 po sitivity may be a prognostic factor and an indicator of the need for steroi d therapy in IgA nephropathy.