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).