Tumor-infiltrating FoxP3⁺ T cells express the Helios antigen.

<p>Mice harboring one of the four types of tumors (A20 B cell lymphoma, CT26 colon cancer, 4T1 breast cancer, and B16 melanoma) were examined for expression of Helios by FoxP3⁺ T cells. (A) Helios expression by FoxP3⁺ T cells in tumors and various secondary lymphoid tissues such as the draining lymph node (D-LN), other peripheral lymph nodes (PLN), and mesenteric lymph node (MLN). (B) Frequencies of Helios-negative FoxP3⁺ T cells in tumors and secondary lymphoid tissues. (C) Detection of Helios⁺ FoxP3⁺ T cells in tumors by confocal microscopy. Arrows indicate T cells that co-express FoxP3 and Helios in tumors. Representative and combined (n = 4) data are shown. “*” indicates significant differences from tumors.