Detection of CCR8, TNFR2, CTLA-4, and TGF-β1 proteins in CD8⁺CD25⁺ and CD8⁺CD25^- human thymocytes. CCR8 (A) and TNFR2 (B) were detected by flow cytometry on the surface of freshly prepared thymocytes, and CTLA-4 (C) and TGF-β1 (D) in the cytoplasm of fixed thymocytes. A representative experiment is shown.