Background IL-6 is involved in the induction of acute phase protein synthesis in liver cells, as well as in other systemic changes associated with infection and tissue injury. IL-6 is probably produced by mesangial cells in patients with mesangial proliferative glomerulonephritis (MPG).

Objectives The aim of this study was to determine IL-6 levels in urine and plasma of patients with primary glomerular disease ? MPG and of patients with systemic lupus erythematosus who had MPG (II class of lupus nephritis according to WHO).

Methods The study included 23 patients and 10 healthy volunteers. 12 out 23 patients had MPG and 6 had SLE and MPG. 5 out 23 patients had membranoproliferative glomerulonephritis. Plasma and urine IL-6 levels were determined using sensitive bioassay.

Results Measurable quantities of IL-6 were detected in the urine (mean ± SEM = 24.75 ± 0.61 pg/ml; n = 10) as well as in the plasma (14.18 ± 0.43 pg/ml; n = 10) of healthy controls. Increased urine IL-6 levels were found in patients with primary and secondary (with SLE) MPG (29.75 ± 0.75; n = 17; p < 0.01), while in patients with membranoproliferative glomerulonephritis the IL-6 concentration did not differ from the control values (25.24 ± 1.4; n = 5; p > 0.05). In plasma the mean IL-6 concentration in patients with MPG and SLE was slightly but not significantly higher than in the healthy subjects.

Conclusion The data show that the presence of IL-6 in urine but not in plasma, may be a valuable indication of the disease in the majority of patients with primary MPG and patients with SLE who had MPG.