A retrospective analysis of patients treated at Emory showed that administration of GM-CSF and interferon-alpha-2b was well-tolerated and affected long-term remissions in a small number of relapsed patients (after allogeneic transplant). Pre-clinical and clinical data from ours and other centers showed that relapsed leukemic blasts have down-regulation of co-stimulatory molecules and a tendency to evade the immune system. Cytokines can up-regulate co-stimulatory molecules on leukemic blasts and have been shown to increase the cytotoxicity of T-cells. This effect may be beneficial as a graft vs. leukemia effect for patients with relapse after allogeneic transplant.