Aptamers Generated by Multi-Strategy Selection Target FcγRI and Block IgG Fc-FcγRI Interaction

FcγRI, a high-affinity receptor for the Fc region of IgG, plays a pivotal role in bridging humoral and cellular immunity by mediating phagocytosis, and cytokine secretion to combat pathogens and maintain immune homeostasis. Developing high-affinity ligands for FcγRI holds significant promise for regulating immune effector functions and facilitating advanced diagnostic applications. Here, we integrated Capture-SELEX, PAGE-SELEX, and Cell-SELEX to isolate a panel of aptamers with excellent specificity for human FcγRI. These aptamers demonstrated a remarkable ability to bind to the IgG Fc-binding site of FcγRI, effectively blocking the interaction between FcγRI and IgG Fc. Through truncation and site-directed mutagenesis, we further engineered aptamers with enhanced affinity (<i>K</i>_d: 0.98 to 0.15 nM), resulting in significantly improved inhibition of FcγRI-IgG Fc interaction (IC₅₀: 3.55 to 0.88 nM). The optimized aptamers have been applied to analyze FcγRI-expressing cells within clinical blood samples, detect surface FcγRI upregulation in activated immune cells, and enrich FcγRI-high expressing cells─underscoring their potential for both research and translational applications.