Effect of prednisolone therapy on serum concentrations of soluble interleukin-2 receptor in patients with IgA nephropathy

Background It is not known whether steroid therapy affects the serum level of soluble interleukin-2 receptor (sIL-2R) in patients with glomerulonephritis. We therefore examined the relationship between serum level of sIL-2R and indicators of disease activity in patients with immunoglobulin (Ig) A nephropathy, and serum levels of sIL-2R in patients before and after prednisolone therapy. Methods Serum sIL-2R levels were determined using an immunoenzymatic technique in 97 patients with IgA nephropathy, and the effects of prednisolone therapy on sIL-2R levels were assessed in 15 patients with IgA nephropathy. Results An increased level of serum sIL-2R was shown at the time of renal biopsy in all patients with IgA nephropathy. Moreover, the serum sIL-2R levels were positively correlated with urinary protein excretion (P<0.01,r=0.32) and negatively correlated with creatinine clearance (P<0.01,r=−0.42) in all patients with IgA nephropathy. Prednisolone therapy (0.8 mg/kg per day) caused a significant reduction in the serum sIL-2R level in accordance with the decrease in daily proteinuria in 15 patients with IgA nephropathy. Conclusions These results suggest that the measurement of serum sIL-2R would be useful in evaluating the degree of disease activity, and the serum sIL-2R levels may be a useful indicator for estimating the effect of prednisolone therapy in patients with IgA nephropathy.