The 9E9 monoclonal antibody specifically binds to Fc receptor, IgG, low affinity IV (FcγRIV), which is also known as CD16-2. FcγRIV is encoded by Fcgr4 and belongs to the family of receptors for the Fc region of IgG (FcγRs), which also includes FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16) within the Ig superfamily. FcγRIV is expressed on monocytes, macrophages, dendritic cells, and neutrophils. FcγRIV, which serves as a ligand-biding subunit, requires the common Fcγ chain for expression and signaling. This complex serves as a cell activating receptor when bound by IgG2a or IgG2b. FcγRIV plays various roles in inflammation including neutrophil trafficking and mast cell degranulation. FcγRIV can also function as a low-affinity IgE receptor and promote IgE-induced inflammation. The 9E9 antibody can reportedly inhibit cellular FcγRIV (CD16-2) function and block non-antigen-specific binding of immune complexes to improve the quality of immunological assays.
The antibody was conjugated to BD Horizon™ BV421 which is part of the BD Horizon Brilliant™ Violet family of dyes. With an Ex Max of 407-nm and Em Max at 421-nm, BD Horizon BV421 can be excited by the violet laser and detected in the standard Pacific Blue™ filter set (eg, 450/50-nm filter). BD Horizon BV421 conjugates are very bright, often exhibiting a 10 fold improvement in brightness compared to Pacific Blue conjugates.