CD27 and tuberculosis: For example, CD27 has been associated with active disease and tissue destruction in TB [19]; CD137 has been used to identify reactive T cells in response to TB antigens [20]; CD38, an early immune marker of T cell activation, was found to be significantly superior to CD27 in the accurate diagnosis of TB [21]; HLA-DR, usually highly expressed during the late stage of T cell activation [22, 23], is believed to have the potential to distinguish patients with ATB from LTBI individuals [24].