The prognostic significance of urinary interleukin 6 in IgA nephropathy.

Our previous study has shown that interleukin 6 (IL-6), a multifunctional cytokine, is closely associated with the pathogenesis of mesangial proliferative glomerulonephritis (mesPGN). To investigate whether urinary IL-6 can be used as an indicator in the prognosis of patients with IgA nephropathy, we monitored IL-6 activity in the urine of patients with IgA nephropathy for 10 months and compared IL-6 activity with clinical data as well as the histological changes of the kidneys obtained from the patients. It was found that among the patients who had continuously high urinary IL-6 activity, histological progression of IgA nephropathy was observed. On the other hand, among the patients whose urinary IL-6 became undetectable during the 10-month follow-up, histological improvement of IgA nephropathy was observed. These data suggest that the measurement of urinary IL-6 is a helpful tool for monitoring the progression of IgA nephropathy.