Introduction of Immunoglobulin

Immunoglobulin (Ig) is a kind of globulin with antibody activity or chemical structure similar to that of antibody widely present in mammalian serum, lymph fluid, tissue fluid and exocrine fluid, and it is an important component in the body's defense against diseases and has an important role in disease research, drug development and vaccine evaluation. Antibody (Ab) is an immunocompetent immunoglobulin secreted by B-cells after receiving antigenic stimulation, i.e., immunoglobulin that can bind specifically to antigen. Therefore, all antibodies are immunoglobulins, while immunoglobulins are not all antibodies.The Ig molecule consists of two identical light chains (L chains) and two identical heavy chains (H chains), and the L and H chains are connected by disulfide bonds to form a tetrapeptide chain molecule, which is known as the monomer of the Ig molecule, and constitutes the basic structure of the immunoglobulin molecule. Immunoglobulins are classified into five types according to the structure of the constant region of the H chain: IgG, IgA, IgM, IgD and IgE.

The inventory of reagents associated with immunoglobulin that KMD Bioscience can offer:

Introduction of IgG

Immunoglobulin G (IgG) is the main component of serum immunoglobulin, which accounts for about 75% of the total immunoglobulin, and is mainly synthesized and secreted by plasma cells in the spleen and lymph nodes, and exists in the form of monomer. As the main component of anti-bacterial, anti-toxin and anti-virus antibodies, IgG is also an important material basis for the process of the body's immunity against infection. It is also the only immunoglobulin that can pass through the placental barrier, and plays an important role in the fight against infections in mammalian newborns and neonates. That is why immunoglobulins are usually referred to as IgG.

Increased serum IgG: seen in systemic lupus erythematosus, atrophic portal hepatic cirrhosis, chronic active hepatitis, rheumatoid arthritis, subacute bacterial endocarditis, IgG-type myeloma, certain infectious diseases, and IgG-type monoclonal gammopathy. Reduced serum IgG: seen in antibody deficiency, immunodeficiency syndromes, non-IgG type multiple myeloma, heavy chain disease, light chain disease, nephrotic syndrome, certain leukemias, burns, allergic eczema, aspergillosis, and muscular dystrophy.

Figure 1 Schematic diagram of IgG structure

Introduction of IgA

Immunoglobulin A (IgA), second only to IgG in serum, accounts for 10-20% of serum immunoglobulin content. There are two types: serotype and secretory type, but serotype IgA does not show important immune function in serum. Secretory IgA is the main antibody of local anti-infection immunity in the mucous membrane of the body. It is mainly found in secretory fluids, such as saliva, tears, colostrum, nasal and bronchial secretions, gastrointestinal fluids, urine, sweat, etc. IgA cannot pass through the placenta. IgA is not present in the serum of newborns, but secretory IgA can be obtained from breast milk, and IgA begins to appear in the blood after 4-6 months of life.The immune response can be mounted and secretory antibodies, known as SIgA, can be produced.

IgA is secreted as a monomer or dimer, depending on its location. The dimeric IgA binds to the polymeric Ig receptor (pIgR), undergoes transcytosis, and is cleaved to form the secretory component. The release of SIgA into the mucosal lumen allows it to interact with pathogens, preventing antigenic adhesion and penetration, neutralizing viruses and conditioning antigens for clearance.

Figure 2 Schematic diagram of IgA structure

Introduction of IgM

Immunoglobulin M (IgM) accounts for about 5%-10% of the total serum immunoglobulin, and monomeric IgM is expressed on the cell surface as membrane-bound (mIgM), constituting the B-cell antigen receptor (BCR). Secretory IgM is pentameric and is the largest molecular weight Ig, called macroglobulin. It is mainly secreted and synthesized by plasma cells in the spleen and lymph nodes and is divided into two subtypes, IgMl and IgM2. Mainly distributed in serum, IgM has a powerful bactericidal, activating complement, immunomodulation and agglutination effects, but also involved in the pathological process of certain autoimmune diseases and hypersensitivity reactions.

When the organism is infected, the first antibody to appear is IgM, so the detection of IgM level can be used as an early diagnostic indicator of infectious diseases. Due to its high molecular weight, IgM is not easily permeable to blood vessels and is the first line antibody against intravascular infections, so it plays an important role in preventing the occurrence of bacteremia and sepsis.1. Increase in serum IgM: seen in macroglobulinemia, rheumatoid arthritis, systemic lupus erythematosus, liver disease, and some infectious diseases, etc.2. Decrease in serum IgM: seen in primary nongammaglobulinemia, secondary immune deficiencies, etc.3.

Figure 3 Structure of IgM

KMD Bioscience's current diagnostic active ingredients are related to infectious diseases, tumors, inflammation, thyroid function, hormones and other directions. KMD Bioscience can provide a wide range of bioactive raw materials and technical services for IVD, which are widely used by domestic and foreign manufacturers of related reagents. These include, but are not limited to, customized development of antigens and antibodies, antigen-antibody labeling and coupling, antibody pair screening and purification, immunochromatography, enzyme immunoassay and chemiluminescence system optimization and process debugging, and other technologies.