Fc-Fragment

Fc fragment

The Fc fragment is part of the immunoglobulin molecule that is cleaved off by the enzyme papain. It consists of two C-terminal regions of immunoglobulin heavy chains. Unlike the full antibody molecule, the Fc fragment does not interact directly with the antigen. However, due to the Fc fragment, many effector functions of antibodies are realized. In particular, it is the Fc fragment that mediates the ability of immunoglobulins to attach to cells, fix complement, and also participate in the reaction of passive cutaneous anaphylaxis. Thus, despite the fact that the Fc fragment is not involved in antigen recognition, it plays an important role in the implementation of the immune response.

Fc fragment: role in the immune system

The Fc fragment (from the English Fragment crystallizable) is a part of the immunoglobulin (Ig) molecule that is cleaved off with the help of papain, which is a proteolytic enzyme. The Fc fragment consists of two C-terminal regions of heavy chains and does not interact with the antigen. However, it is the Fc fragment that is associated with the ability of immunoglobulin to attach to cells, bind complement, and participate in the reaction of passive cutaneous anaphylaxis.

Immunoglobulins are glycoproteins that are synthesized by plasma cells (B-lymphocytes) in response to the introduction of an antigen into the body. Immunoglobulins play an important role in protecting the body from infections and other pathogens. They may indirectly participate in the destruction of pathogens or assist other cells of the immune system in this process.

Immunoglobulins consist of two types of chains - heavy and light. Each immunoglobulin has two identical heavy and two identical light chains. Heavy chains have in their structure a loop (Fab fragment), capable of binding to antigen, and an Fc fragment. Light chains do not have an Fc fragment and do not bind to antigen.

The Fc fragment has several important functions in the immune system. It ensures that immunoglobulin binds to receptors on cells of the immune system, such as macrophages, neutrophils, natural killer cells and other cells, which allows them to perform their functions. For example, binding of immunoglobulin to receptors on macrophages results in phagocytosis (engulfment) of immunoglobulin-bound pathogens.

The Fc fragment also ensures the binding of immunoglobulin to complement proteins, which leads to activation of the complement system and increased immune response. In addition, the Fc fragment is involved in the reaction of passive cutaneous anaphylaxis. In this reaction, immunoglobulins bind to an antigen that has already entered the body and cause an allergic reaction.

In conclusion, the Fc fragment is an important part of the immunoglobulin molecule, which ensures the binding of immunoglobulin to cells of the immune system and complement proteins, and is also involved in the reaction of passive cutaneous anaphylaxis. Understanding the role of the Fc fragment in the immune system is important for the development of new methods to combat infections and other diseases associated with immune system dysfunction. For example, monoclonal antibodies are developed based on the Fc fragment and are used to treat cancer, autoimmune diseases and other diseases. Also, studies of the Fc fragment can help improve the effectiveness of vaccines and other immunotherapies that rely on stimulation of the immune system. In general, the Fc fragment is an important element of the immune system, which plays a key role in protecting the body from infections and other pathological processes.