[Study of correlation between urinary IL-6 level and mesangial lesion in childhood onset IgA nephropathy].

In the present study, urinary IL-6 levels in 28 patients with IgA nephropathy (IgAN), 10 patients with idiopathic minimal change nephrotic syndrome (IMCNS) and 11 normal controls were measured using by an ELISA method to clarify the role of IL-6 as an autocrine growth factor of mesangial cells. Spot urine was centrifuged at 1000 rpm for 10 minutes at 4 degrees C and the supernatant was utilized as samples. The patients with IgAN were classified into three groups, group I (18 patients); minor glomerular abnormalities, group II (5 patients); focal segmental lesions, group III (5 patients); diffuse glomerulonephritis, according to the WHO classification of glomerular diseases. Geometric mean +/- S.E. of urinary IL-6 was 1.619 +/- 0.075 in patients with IgAN (group I; 1.432 +/- 0.078, group II; 1.920 +/- 0.181 and group III; 1.987 +/- 0.055), 0.681 +/- 0.174 in IMCNS and 0.506 +/- 0.181 in normal controls, respectively. Urinary IL-6 levels were significantly elevated in patients with IgAN than in IMCNS and normal controls, but did not necessarily reflect the severity of mesangial lesions. Some patients with prominent segmental mesangial proliferation in group II showed much higher urinary IL-6 levels than those in group III. Elevated urinary IL-6 levels in group II may be involved in higher activity of mesangial proliferation, and the decreased production of IL-6 observed in some patients of group III may related to advanced glomerular sclerosis. The results suggests that IL-6 plays an important role as a mesangial proliferative growth factor in IgAN and that measurement of urinary IL-6 levels by an ELISA method is a useful method to estimate the degree of mesangial proliferation and disease activities easily and noninvasively in patients with IgAN.