Response to Comment on “Helios+ and Helios− Cells Coexist within the Natural FOXP3+ T Regulatory Cell Subset in Humans”

Ayyoub et al. raise two long-standing questions in their comment addressing the publication by Himmel et al. ([1][1]): what is the best way to define T regulatory cells (Tregs) from different origins in humans; and which population of Tregs is optimal for cell therapy applications? A consistent