The addition of monoclonal antibody therapy is an attractive approach in the treatment of relapsed and refractory ALL since it targets both B and T progenitor ALL subtypes and has different mechanisms of action and side effects than chemotherapy. Alemtuzumab is a humanized monoclonal antibody to CD52 which is expressed on the majority of neoplastic lymphocytes, including 70% of ALL and 100% of Philadelphia positive ALL. The CALGB evaluated alemtuzumab as consolidation in front-line therapy for patients with ALL and demonstrated feasibility and found alemtuzumab administration at 30mg subcutaneously administered for 12 doses to be safe and well tolerated in a frontline consolidation setting in ALL. In the present protocol targeting refractory and relapsed ALL patients, the maximal alemtuzumab dose will be 30 mg as in Stock's study, but will be administered intravenously in order to improve the induction chemotherapy pharmacokinetics. Premedication with dexamethasone, benadryl, and acetaminophen will be given to all patients prior to alemtuzumab infusion to prevent infusional reactions associated with intravenous dosing.