In humans, there are five heavy chain isotypes: α– IgA, δ– IgD, γ– IgG,ε – IgE, and μ– IgM. The isotypes often appear in the corresponding forms are dimer, monomer, monomer, monomer, and pentamer, in respectively. IgG is distributed throughout the body except the brain. The brain is the central control of systemic activity. Unless infected here, antibodies should not be present. The presence of the antibodies can be found in different locations:
■ IgM only exists in the heart and blood circulation system, because of its large molecular weight, it will not run out of blood vessels.
■ Meric Dimeric IgA mainly exists in the mucosal layer, such as the oral cavity, respiratory tract, digestive tract, urogenital tract, and mammary glands. Therefore, breast milk is rich in IgA, and infants who consume breast milk can obtain longer protection.
■ IgE spreads across the surface and mucosal layers of the skin.
■ IgM only exists in the heart and blood circulation system, because of its large molecular weight, it will not run out of blood vessels.
■ Meric Dimeric IgA mainly exists in the mucosal layer, such as the oral cavity, respiratory tract, digestive tract, urogenital tract, and mammary glands. Therefore, breast milk is rich in IgA, and infants who consume breast milk can obtain longer protection.
■ IgE spreads across the surface and mucosal layers of the skin.