| 背景 | This is a purified Armenian hamster IgG monoclonal antibody, clone 9E9, raised against mouse CD16.2 (FcgammaRIV, encoded by Fcgr4). It is produced as a low-endotoxin, carrier-free, research-use-only preparation suitable for in-vivo administration and functional in-vitro work, and is available in bulk milligram to gram quantities to support repeat-dose animal studies and larger cohorts. Clone 9E9 is one of the most widely used reagents for detecting and blocking mouse FcgammaRIV, with validated applications in blocking and flow cytometry. Because FcgammaRIV is an activating Fc-gamma receptor engaged by IgG2a and IgG2b, 9E9 is a standard tool for isolating the contribution of this single receptor to antibody-mediated effector responses, including in models of antibody-dependent cytotoxicity, autoimmunity, inflammation, and tumour immunotherapy. Low endotoxin (research grade less than 1 EU/mg; ultra-low grade less than 0.5 EU/mg) minimises confounding innate stimulation in sensitive in-vivo assays. Its hamster IgG framework pairs conveniently with commonly available anti-Armenian-hamster secondary and isotype-control reagents for staining and control arms.
CD16.2, also called FcgammaRIV and encoded by Fcgr4, is an activating Fc-gamma receptor found only in mouse and is the structural ortholog of human CD16/FcgammaRIIIA. It is an intermediate-to-high-affinity receptor with a distinctive IgG subclass specificity: it binds mouse IgG2a and IgG2b but not IgG1 or IgG3. FcgammaRIV signals through the associated FcR gamma-chain (ITAM-bearing) to trigger effector functions such as antibody-dependent cellular cytotoxicity, phagocytosis, degranulation, and release of inflammatory mediators. Expression is largely restricted to myeloid cells, prominently neutrophils, monocytes, and macrophages, and is upregulated by inflammatory stimuli while downregulated by certain cytokines. Because it is the principal receptor mediating IgG2a and IgG2b activity in vivo, FcgammaRIV is a key determinant of the in-vivo potency of many therapeutic and depleting antibodies of these subclasses, making it central to studies of antibody effector mechanisms. FcγRIV is expressed on the cell membrane of splenic and bone marrow dendritic cells, monocytes, and macrophages as well as peripheral blood monocytes, neutrophils, thioglycollate-elicited macrophages, and myeloid cells. FcγRIV is absent from lymphoid populations, T cells, B cells, NK cells, and other granulocytes. |
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