FcγRIa/CD64 is a high-affinity receptor for the Fc portion of IgG antibodies, playing a crucial role in immune responses. It is an integral membrane glycoprotein composed of a signal peptide, three extracellular immunoglobulin domains of the C2-type for antibody binding, a hydrophobic transmembrane domain, and a short cytoplasmic tail. CD64 is primarily found on macrophages and monocytes but can be induced on polymorphonuclear leukocytes by cytokines like IFNγ and G-CSF. This receptor has the highest affinity for IgG1 among all Fcγ receptors, making it significant for monoclonal antibody binding and effector functions. It interacts with the common γ chain to trigger cellular activation upon binding to IgG. There are three distinct genes for CD64 in humans—FcγRIA （CD64A）, FcγRIB （CD64B）, and FcγRIC （CD64C）—located on chromosome 1, which produce six different mRNA transcripts through alternative splicing.