RESUMO
INTRODUCTION: Childhood Idiopathic Nephrotic Syndrome (INS) responds to glucocorticoid therapy, however, 60-80% of patients relapse and some of them become steroid non responsive. INS may occur because of T cell dysfunction, abnormal cytokines and podocytopathies which reverse on steroid treatment. The reason of relapses could be imbalances in T cells phenotypes and respective cytokines. Herein, we hypothesize that relapses in INS may occur due to imbalance in T-regulatory and T-effector cell with their respective cytokines and overexpression of P-gp on lymphocytes. METHODS: The frequency of peripheral blood CD4(+)CD25(+)FoxP3(+) Treg, CD4(+)IFN-γ(+) Th1 and CD4(+)IL-4(+) Th2 lymphocytes and their respective cytokines and P-gp expression on peripheral blood lymphocytes (PBLs) were analyzed in INS patients at baseline (n=26), during remission (n=24) and at relapse (n=15). RESULTS: Compared to baseline, the frequency of Tregs was significantly increased at remission and decreased during relapse. In contrast, the frequency of Th1 and Th2 lymphocytes was significantly decreased during remission and increased at the time of relapse. Similarly, expression of P-gp was significantly high at baseline and at the time of relapse as compared to remission. Levels of cytokines IL-10 and TGF-ß in the supernatant of stimulated PBMCs was increased during remission and decreased during relapse. In contrast, levels of IFN-γ and IL-4 were decreased during remission and increased at the time of relapse. CONCLUSIONS: Steroid therapy in INS induces decreased P-gp expression on PBLs along with increased frequency and cytokine response of T-regulatory cells, and reduced frequency and respective cytokine response of Th1 and Th2 cells during remission. However, reversal in the frequency and respective cytokines of T-regs, Th1 and Th2, and P-gp expression on PBLs occurs during relapses on follow-up.