B6-hFCGR1 Mouse

FCGR1 gene encodes FcγRI, a specific receptor for IgG antibodies, also known as CD64. This receptor plays a key role in human immune responses. FcγRI has a high affinity for the Fc portion of IgG antibodies and is the only member of the human FcγRs with a high affinity for monomeric IgG. It plays important roles in both innate and adaptive immune responses ^[1]. FcγRI is expressed on a variety of immune cells, including monocytes, macrophages, dendritic cells, and neutrophils. It plays a critical role in host defense against infection and humoral immunity by influencing processes such as phagocytosis, antibody-dependent cell-mediated cytotoxicity (ADCC), and antigen presentation ^[2-3]. The binding of FcγRI to IgG-coated target cells promotes their phagocytosis by immune cells. This is an important mechanism for clearing infected cells, apoptotic cells, and other foreign particles. In addition, this binding can also promote the release of cytotoxic granules by immune cells, such as natural killer cells and cytotoxic T cells, leading to the killing and lysis of target cells. In antigen presentation, FcγRI binding to IgG-coated antigens promotes dendritic cells to take them up and present them to T cells, which is essential for the initiation of adaptive immune responses. In addition, FcγRI is involved in a variety of important physiological processes, such as wound healing and inflammation. FcγRI plays a critical role in antibody-based immunotherapy, which has important implications for the development of therapeutic drugs and methods for a variety of autoimmune diseases, infectious diseases, and tumors ^[4-5].

This model represents a humanized FCGR1 mouse, generated by substituting the mouse Fcgr1 gene sequence (inclusive of the UTR) with the corresponding human FCGR1 gene sequence. This modification enables the expression of human FcγRI in mice. Homozygous B6-hFCGR1 mice exclusively express human FcγRI receptors, with the proportion of cells expressing human FcγRI mirroring that of cells expressing mouse FcγRI in wild-type mice. Consequently, this model serves as a valuable tool for various research areas, including the evaluation of human IgG antibody affinity, exploration of the ADCC mechanism, investigation into immune cell phagocytosis and antigen presentation. Furthermore, it provides a platform for the preclinical assessment of therapeutic human IgG antibodies.