A monoclonal antibody linked to a toxic substance. It is being studied in the treatment of some types of B-cell cancer. Anti-CD22 immunotoxin is made in the laboratory. It binds to CD22, a protein on the surface of normal B cells and B-cell tumors, and kills the cells. OR A monoclonal antibody directed against the receptor-like leukocyte cell surface glycoprotein CD45 with leukocyte-depleting activity. Upon administration, anti-CD45 monoclonal antibody binds to leukocyte surface-expressed CD45, which may result in the transient depletion of circulating leukocytes including circulating T cell depletion (TCD). CD45, a receptor-like protein-tyrosine phosphatase that consists of several isoforms, is present on all differentiated hematopoietic cells except erythrocytes and plasma cells and is essential for T cell development and lymphocyte activation. Check for active clinical trialsusing this agent.