Human CD64 Protein (In Vivo Grade, Ultra-Low Endotoxin) (ICH3010)

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This product is a recombinant Human CD64 (Fc-gamma receptor I, FcgammaRI; gene FCGR1A) protein, not an antibody. It is expressed in human embryonic kidney (HEK) 293 cells, giving a mammalian glycosylation pattern that better preserves the native folding and Fc-binding surface than bacterial systems. The reagent is manufactured to in-vivo grade with ultra-low endotoxin (<0.5 EU/mg), which minimizes confounding TLR4-driven activation in sensitive cell-based, functional, and animal-adjacent assays. As a purified soluble antigen, it is well suited to biophysical and analytical characterization of IgG-Fc interactions, engineered Fc variants, and Fc-fusion proteins. Validated applications are surface plasmon resonance (SPR), biolayer interferometry (BLI), and ELISA, where the protein serves as an immobilized or analyte partner for affinity and kinetic measurements. Supplied as a bulk, research-use-only (RUO) reagent, it supports antibody engineering, Fc-effector-function screening, and structure-function studies. All content here is guidance for ichorbio to review before publishing. CD64, encoded by FCGR1A, is the only high-affinity Fc-gamma receptor (FcgammaRI) for monomeric IgG, distinguishing it from the lower-affinity FcgammaRII and FcgammaRIII receptors that engage only immune complexes. It is expressed predominantly on monocytes, macrophages, and interferon-gamma- or G-CSF-activated neutrophils, where its surface levels are markedly upregulated during inflammation and infection. CD64 binds the Fc region of human IgG1, IgG3, and IgG4 with high affinity (and IgG2 more weakly), coupling through the FcR gamma-chain to trigger phagocytosis, antibody-dependent cellular cytotoxicity (ADCC), respiratory burst, cytokine release, and antigen presentation. Because it captures monomeric IgG, CD64 is a central determinant of the effector function and pharmacokinetics of therapeutic antibodies, making it an important target for characterizing Fc engagement.