High urinary interleukin-2 in late post-transplant period portends a risk of decline in kidney allograft function: a preliminary study

BACKGROUND: Predictive factors for the rate of decline in kidney allograft function beyond the first post-transplant year have not been thoroughly studied. We aimed to determine whether a single measurement of serum and urinary interleukin 2, interleukin 8 and interleukin 10 at 1–15 years after kidney transplantation could predict a decline in estimated glomerular filtration rate (eGFR) over a 2-year period. RESULTS: Greater serum concentrations of interleukin 8 and interleukin 10 in 30 recipients of kidney allograft at enrollment were associated with lower eGFR after 1 year (beta = − 0.616, p = 0.002 and beta = − 0.393, p = 0.035, respectively), whereas serum concentrations of interleukin 8 also demonstrated significant association with eGFR after 2 years of follow-up (beta = − 0.594, p = 0.003). Higher urinary interleukin 2 concentrations were associated with lower eGFR at baseline (rho = − 0.368, p = 0.049) and after the first (beta = − 0.481, p = 0.008) and the second year (beta = − 0.502, p = 0.006) of follow-up. Higher urinary interleukin 2 concentrations predicted certain decline in eGFR of ≥ 25% from baseline after 1 year of follow-up in logistic regression: odds ratio = 2.94, confidence interval 1.06–8.18, p = 0.038. When combined with time after transplantation, urinary interleukin 2 demonstrated good accuracy in predicting rapid decline in eGFR by > −5 mL/min/1.73 m(2)/year (area under the receiver-operator characteristic curve: 0.855, confidence interval 0.687–1.000, and p = 0.008). CONCLUSIONS: Our findings suggest that urinary interleukin 2 in the late period after kidney transplantation has promise in identifying patients who are at risk for progressive loss of graft function in a short-time perspective and need closer monitoring.