Why is IgG half-life so long?
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Why is IgG half-life so long?
Immunoglobulin G (IgG) has an unusually long serum half-life in comparison to proteins of a similar size. It is well-known that this phenomenon is due to IgG’s ability to bind the neonatal Fc receptor (FcRn) in a pH-dependent manner.
What is FcRn antibody?
Abstract. The biomedical applications of antibodies as prophylactics, therapeutics and diagnostics are developing rapidly. Neonatal Fc receptor (FcRn) is a major IgG Fc receptor capable of facilitating the translocation of IgG. FcRn can protect IgG from intracellular catabolism, thereby increasing its half-life.
What does Fc stand for in FcRn?
Neonatal Fc receptor
| Fc fragment of IgG, receptor, transporter, alpha | |
|---|---|
| Identifiers | |
| RefSeq | NM_004107 |
| UniProt | P55899 |
| Other data |
What is FcRn in immunology?
The neonatal Fc receptor for IgG (FcRn) is responsible for the transfer of passive humoral immunity from the mother to the newborn in rodents and humans. Throughout life, FcRn contributes to effective humoral immunity by recycling IgG and extending its half-life in the circulation.
Which antibody has the shortest half-life?
Therefore, the half-lives determined with monoclonal antibodies possessing the same V region represent the half-life of the serum immunoglobulins. In this way we calculated the half-life of IgM as 2 days, IgG3 and IgG1 as 6-8 days, IgG2b has a half-life of 4-6 days. IgE has a half-life of 12 h.
How long is the half-life of IgG antibodies?
For total IgG, the half-life found was 25.8 days; for IgG1 it was 29.7 days; for IgG2 it was 26.9 days; and for IgG3 it was 15.7 days. The results are similar to those reported for endogeneous IgG. Half-lives for antibodies to S.
Where is FcRn found?
Human FcRn has been found in both fetal endothelium and apically localized vesicles within the syncytiotrophoblasts that are in direct contact with maternal blood (113, 118, 139, 140). IgG is the only antibody class that is transported across the placenta (141, 142), and this process is dependent on FcRn (66).
What is FcRn inhibitor?
The neonatal fragment crystallizable (Fc) receptor (FcRn) functions as a recycling mechanism to prevent degradation and extend the half-life of IgG and albumin in the circulation. Several FcRn inhibitors selectively targeting IgG recycling are now moving rapidly toward clinical practice in neurology and hematology.
How does FcRn protect IgG?
FcRn functions within intracellular endosomes, where it binds IgG and albumin at distinct, nonoverlapping sites under acidic but not neutral pH conditions (16). Thus, FcRn is considered a saturable “protection” receptor that serves to prevent the catabolism of IgG and albumin (8).
How does IgG bind to FcRn?
FcRn is expressed by endothelial cells, which internalize serum components including soluble IgGs from the bloodstream by pinocytosis. IgG binding to FcRn is pH-dependent;11 the acidic pH (pH 6.0) inside the endosomal compartment allows the IgGs to bind to FcRn.
What is the role of the FcRn receptor?
FcRn functions as a recycling or transcytosis receptor that is responsible for maintaining IgG and albumin in the circulation, and bidirectionally transporting these two ligands across polarized cellular barriers.
Which antibody has the longest half-life?
IgG. IgG is the predominant isotype found in the body. It has the longest serum half-life of all immunoglobulin isotypes.
What is the half-life of IgM?
5 to 6 days
In serum, the normal range for IgM is 85 to 350 mg/100 mL, and the half-life is 5 to 6 days.
Which immunoglobulin has longest half-life?
IgG is the most abundant antibody in normal human serum, accounting for 70-85% of the total immunoglobulin pool (1). It is monomeric with a molecular weight of approximately 150 kDa, is the major antibody of the secondary immune response and has the longest half-life (20-24 days) of the five immunoglobulin classes.
What cell types express FcRn?
FcRn is also widely expressed by hematopoietic cells including monocytes, macrophages, dendritic cells (DC), neutrophils and B cells where, in contrast to polarized epithelial cells, it is detected in significant quantities on the cell surface (27).
What is FcRn recycling?
Which immunoglobulin has the shortest serum half-life?
In the blood, IgE is present at the lowest concentration of any of the Ig isotypes (with roughly five orders of magnitude less IgE than IgG) and has the shortest half-life.
