The cluster of differentiation 20 （CD20, aka Ly-44, or B-lymphocyte antigen） is a ~35 KDa cell surface protein mainly expressed by resting and activated B lymphocytes, but not plasma cells [1]. CD20 is also expressed by most malignant B cells, which makes it an ideal target for antibody-based immunotherapies against lymphoid malignancies [1-4]. For example, Rituximab, Obinutuzumab, and Ofatumumab are FDA-approved monoclonal anti-human CD20 antibodies for the treatment of B-cell non-Hodgkin’s lymphoma and B-cell chronic lymphocytic leukemia [1-4]. These antibodies mediate the target cell destruction through different mechanisms including direct signaling of apoptosis, complement activation （CDC）, and cell-mediated cytotoxicity （ADCC）.

The anti-mCD20 18B12 mAb is commonly used for in vivo depletion of the CD20+ B cell population to study the role of B cells in various immune responses, including auto-immune or tumoral contexts [1, 7].
Anti-mCD20-mIgG2a is provided in an Invivo grade, a high-quality standard specifically adapted to in vivo studies.