Research progress on neonatal Fc receptor and its application.

Neonatal Fc receptor (FcRn) is a specific receptor for immunoglobulin G (IgG) and albumin, which binds to them in a pH-dependent manner and prevents them from lysosomal degradation to keep a long plasma half-life. In addition, FcRn plays an important role in transmembrane transport of IgG and albumin and in antigen presentation. In autoimmune diseases, anti-FcRn antibody can promote the degradation of pathogenic IgG by competitive binding to FcRn. In infectious diseases, the half-life of drugs can be prolonged by increasing the affinity between therapeutic antibody and FcRn, while the combination of viral antigen and Fc fragment of IgG can cause local immune response of mucosa for disease prevention and treatment. In cancer, albumin as a carrier of anticancer drugs can achieve efficient drug delivery, and FcRn itself may be used as a predictor of the prognosis of cancer patients. This review details the functions of FcRn, highlights its role in autoimmune diseases, infectious diseases and cancer, as well as the mechanism of drug development based on FcRn, to provide a reference for the clinical application and drug development of FcRn.