A humanized recombinant monoclonal antibody directed against CD33, a cell surface antigen found on myeloid leukemia blasts and early hematopoietic progenitor cells. Lintuzumab stimulates antibody-dependent cell-mediated cytotoxicity (ADCC) against tumor cells expressing CD33, resulting in a decrease in tumor burden. The humanized version of this monoclonal antibody exhibits less immunogenicity and improved binding affinity compared to its murine counterpart. or A substance being studied in the treatment of myelodysplastic syndromes and some types of leukemia. It binds to CD33, a protein on the surface of certain normal blood stem cells and some abnormal blood cells. It causes the immune system to kill these cells. Lintuzumab is a type of monoclonal antibody. Also called MoAb HuM195 and monoclonal antibody HuM195.