FOXP3 and angioimmunoblastic T-cell lymphoma: PBMC and LIL from AILD patients were exposed to 0 IU/ml or 5 IU/ml Proleukin for 18 h and effects on markers of T cell activation and Treg function by T cell subsets were assessed; 5 IU/ml Proleukin increased significantly the levels of CD25, CTLA‐4 and FoxP3 on peripheral blood Treg of AILD patients (Fig. 2a and Supporting information, Fig. 3).