CD161+ regulatory T cells do not express an invariant TCR. Frequency of TCR-Vβ expression was assessed using a flow cytometry panel to detect 24 Vβ families, in healthy adult CD4+ T cells, CD161–FoxP3+CD4+, CD161+FoxP3+CD4+, CD161−FoxP3–CD4+, and CD161+FoxP3–CD4+ cell populations as shown (n = 5). Data were gated on the specific population and then each TCR-Vβ. Pie charts show proportion of all cells positive for a specific TCR-Vβ (which identify a mean of 70.18% of all cells within respective subset).