IgG antibodies are the most common and the most important. They circulate in the blood and other body fluids, defending against invading bacteria and viruses. The binding of IgG antibodies with bacterial or viral antigens activates other immune cells that engulf and destroy the antigens.
As the smallest antibody, IgG moves easily through cell membranes. IgM is present in the blood and is the largest antibody combining five Y-shaped units. It acts similarly to IgG in protecting against antigens, but because of its size, it cannot cross membranes. To know more about antibodies, you can also browse https://www.bosterbio.com/featured-products.
IgM is the main antibody produced in the first attack by a specific bacterial or viral antigen, whereas IgG is usually produced in subsequent infections caused by the same pathogen.
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IgA antibodies are found in tears, saliva, and mucus, as well as in secretions from the respiratory, reproductive, gastrointestinal, and urinary tracts. IgA neutralizes bacteria and viruses and prevents them from entering the body or reaching internal organs.
IgE is only found in mammals. IgE is the least common isotype and is synthesized by plasma cells. IgE also plays an important role in type I hypersensitivity, which manifests itself in various allergic diseases such as allergic asthma, food allergies, certain forms of chronic urticaria, and atopic dermatitis. IgE also plays a role in allergen reactions.
IgD is present in species from cartilaginous fish to humans. The function of IgD is to signal the activation of B cells. When activated, the cells are ready to protect the body. During B cell differentiation, IgM is the exclusive isotype expressed by immature B cells.
IgD begins to express when B cells leave the bone marrow to colonize peripheral lymphoid tissue. Mature B cells co-express IgM and IgD. IgD may play a role in allergic reactions. IgD can also bind to basophils and mast cells and activate these cells to produce antimicrobial factors involved in respiratory immune protection in humans.