複選題32. Which of the following is a feature of regulatory T cells (Treg)? (Select all that apply.) (A) Treg express CD8 and control effector cells by inducing apoptosis (B) Treg express high levels of CD25 (IL-2 receptor a (alpha) chain) and secrete pro-inflammatory cytokines such as IFN-y (gamma) (C) Physical association between Treg and their target cells is mandatory for Treg function (D) By interacting with dendritic cells in secondary lymphoid tissue, Treg prevent the interaction and activation of naive T cells (E) Treg secrete TGF-B (beta) and suppress effector T-cell function