A population of off-the-shelf (OTS) healthy, donor-derived CD4 and CD8 double-negative T-lymphocytes (allo-DNTs), with potential immunomodulating and anti-leukemic activities. The DNTs are expanded ex vivo in order to enhance their tumor destroying potential. Upon administration of the allo-DNTs RC1012, the receptor type II integral membrane protein (KLRK1; NKG2D) and DNAX accessory molecule 1 (cluster of differentiation 226; CD226; DNAM-1) expressed on the DNTs recognize and bind to their cognate ligands expressed on leukemia cells. Upon binding, the DNTs release interferon-gamma (IFN-g), thereby destroying the tumor cells. NKG2D, a member of the CD94/NKG2 family of C-type lectin-like receptors, and DNAM-1, a member of the immunoglobulin superfamily containing 2 Ig-like domains of the V-set, play a key role in natural killer cell (NK)-mediated tumor cell killing. Certain tumor cells express higher levels of NKG2D and DNAM-1 ligands on their surfaces, thereby increasing their susceptibility to DNT-mediated cell lysis.