It has also been demonstrated that HLA-DR restricted CD4+ T cell clones were cytotoxic for CML cells which processed and presented exogenous antigen (PPD); this led the respective authors to the conclusion that allogeneic donor CD4+ T cells might be sufficient for the induction of graft-versus-leukaemia (GvL) effect [23]. The gene discussed is CD4; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.