The 3D3 monoclonal antibody specifically recognizes FcγRII (CD32), a 40 kDa, polymorphic type I transmembrane glycoprotein that serves as a low affinity receptor for aggregated IgG. This highly glycosylated molecule (encoded by at least two different genes) is expressed on monocytes, granulocytes, platelets and B cells. Unlike the FLI28.26 mAb, the 3D3 mAb detected a polymorphic CD32 antigen expressed on B cells of all donors, but only on platelets, monocytes and granulocytes of some donors. The platelets from 3D3+ donors respond to certain stimulatory mAb such as CD165 (clone SN2) which results in aggregation. On the other hand, the platelets from 3D3 negative donors do not form aggregates after stimulation. Individuals can be divided into two groups as responder and non-responder depending on expression, or non-expression, of 3D3. In comparison to the 3D3 mAb, the FLI8.26 mAb detects a monomorphic CD32 antigen expressed on all human donors.
The antibody was conjugated to BD Horizon Red 718, which has been developed exclusively for BD Biosciences as a better alternative to Alexa Fluor® 700. BD Horizon Red 718 can be excited by the red laser (628 – 640 nm) and, with an Em Max around 718 nm, it can be detected using a 730/45 nm filter. Due to similar excitation and emission properties, we do not recommend using R718 in combination with APC-R700 or Alexa Fluor® 700.