Anti-CD20 Antibody (mAb 1.5.3) is a fully human IgG1 anti-CD20 antibody. It enhances pro-apoptotic activity in vitro and mediates complement-dependent and antibody-dependent cytotoxic effects. In various tumor xenograft models, this antibody shows increased anti-tumor activity. In primate pharmacodynamics models, it exhibits excellent B cell depletion in lymphatic organs and bone marrow. It is applicable in the study of B cell malignancies.