CD4 and Hand-foot syndrome: Histological studies of human skin reveal that the majority of CD4+/Foxp3+ Tregs are preferentially associated with HFs, and rarely the interfollicular dermis or within the epidermis itself.16, 17, 18, 19,31 Flow cytometric analyses further revealed higher number of Tregs in the scalp and the face, which contain more HFs than other body sites.