Ceplene/IL-2 remission maintenance therapy has been shown to significantly prolong Leukemia Free Survival in patients with Acute Myeloid Leukemia (AML) in first complete remission. This is an international, multicenter, open-label study to evaluate the effects of remission maintenance therapy with Ceplene/IL-2 in adult patients with AML in CR1 on specific immune system cells (T and NK cells) and prospectively defined markers of immune response that are known to reflect T and NK cell ability to combat AML.