What is FcRn? And Could blocking FcRn redefine the treatment of dozens of autoimmune diseases?

Some autoimmune diseases are driven by immunoglobulin G (IgG) antibodies that mistakenly attack different parts of the body. Thanks to an emerging area of science, a new class of medicines may help advance the treatment landscape for many of these diseases, and improve symptoms for numerous people. The approach revolves around a breakthrough discovery about the neonatal Fc receptor (also known as FcRn) and its role in recycling IgG antibodies.

What is FcRn and what does it do?

FcRn – shorthand for “neonatal Fc receptor” – is a protein and Fc receptor found in several types of tissues and cells in the body. It plays a role at two different phases of our lives:

  • In early development, FcRn is responsible for passing immunity from mother to child
  • Over a person’s lifetime, FcRn helps maintain the number of antibodies present in a person’s body

FcRn recycles some of the immune system’s frontline forces – antibodies called IgGs. These antibodies have binding sites that fit with FcRn receptors, allowing them to avoid degradation. When an IgG antibody connects to an FcRn receptor, it gets recycled back into the bloodstream and stays in circulation. Unfortunately, the IgG recycling functionality of FcRn may also play a major role in many autoimmune diseases

FcRn and IgG antibodies play a central role in many autoimmune diseases


FcRn blocking may help advance the treatment landscape for many autoimmune disorders.

In the late 1990s, Prof. Sally Ward and her team at the University of Texas Southwestern Medical Center identified the way FcRn receptors bind to IgG antibodies and recycle them into the blood. Years later, Ward and the argenx team began collaborating to find a way to block IgG recycling – hypothesizing that it could mitigate the symptoms of some IgG-mediated autoimmune disorders.

Examples of IgG-Mediated Autoimmune Diseases

Disease Type Symptoms
gMG (Generalized Myasthenia Gravis) Neurological Severe muscle weakness, including difficulty speaking, swallowing, and breathing.
ITP (Idiopathic Thrombocytopenic Purpura) Hematology Bruising and bleeding 
PV (Pemphigus Vulgaris) Dermatological  Blistering of the skin and mucous membranes.
CIDP (Chronic inflammatory Demyelinating Polyradiculoneuropathy) Neurological Weakness in the arms and legs
Bullous Pemphigoid Dermatological Large, fluid-filled blisters, often on areas of skin that flex, such as the lower abdomen, upper thighs, and armpits
Idiopathic Inflammatory Myositis Neurological Muscle inflammation and weakness

FcRn blockers work by reducing the amount of harmful IgG antibodies in circulation

An FcRn blocker works by binding to FcRn receptors and blocking them, resulting in fewer IgG and harmful IgG antibodies from attaching and getting recycled.

FcRn blockers are designed to block IgG recycling at the source, the FcRn receptor.Reducing IgG antibody circulation by blocking FcRn in autoimmune diseases is an area of ongoing research.

Discover Related Stories

Explore more about work to chart a new course in immunology
Immunology Innovation
IIP Spotlight: Working Together To Tackle Asthma

Interested in Learning More?

Get argenx news and updates right to your inbox


Download assets
Get photos, fact sheets, illustrations and more.
Join the team
Dare to do more with a thriving career at argenx.
Follow us
Get the latest news and info via our social media channels.