One such novel therapy, Daclizumab, a humanized anti-interleukin-2 receptor (lL-2R) monoclonal antibody (mAb), acts against activated lymphocytes, thus sharing an important mechanism of action with ATG. The mAb is much less toxic than ATG and may be administered to outpatients at relatively infrequent intervals (every 2 weeks). Treatments with ATG alone and CsA alone have demonstrated varying degrees of success in alleviating the cytopenia of MDS. Our experience suggests that ATG rather than CSA is the more effective agent inducing hematological responses in susceptible MDS patients and that certain variables including the patient's age, whether or not they were HLA DR15, and days of red cell transfusion dependence prior to treatment were predictive of response.