Different patterns of plasma cytokines can be expected in the case of chronic active-antibody-mediated (cAMR) and acute cellular rejection (AR) after kidney transplantation (KTx).
IL-2, 4, 6, 10, 17A, tumor necrosis factor alpha, and interferon gamma were measured in 51 pediatric KTx recipients at time of renal biopsy (17 AR, 14 cAMR, 20 normal). Patients were divided into a training (n = 30) and a validation (n = 21) set.
IL-6 was significantly higher in AR patients and significantly lower in the case of cAMR. In children with s-creatinine increase, IL-6 values were significantly different between AR and cAMR. IL-10 levels showed similar tendencies. For IL-2, 4, 17A, tumor necrosis factor alpha, and interferon gamma, no differences were found. In the independent validation cohort, the receiver operating characteristic area under the curve for IL-6 was 0.79 and 0.70 for AR and cAMR. In children with AR, an IL-6 <1141 fg/ml, and in those with cAMR, an IL-6 >721 fg/ml was associated with a specificity of 86%/76%, a sensitivity of 71%/80%, a positive predictive value of 56%/45%, and a negative predictive value of 92%/94%.
In this pilot study, the plasma IL-6 level is a promising biomarker to identify pediatric kidney transplant recipients free from AR and cAMR and might help to distinguish between both entities, whereas there is only a nonsignificant trend toward the usability of IL-10. Validation in larger cohorts in combination with other biomarkers are warranted.