Isotype (immunology)

Isotype (immunology)

The isotype in immunology refers to the genetic variations or differences in the constant region of the immunoglobulin (Ig) heavy chain. Each isotype is adapted to perform specific roles in the immune response, with different isotypes capable of activating different immune cells. The isotype of an antibody determines its in vivo function and its location in the body.

Types of Isotypes

There are five different isotypes in mammals, which are:

• IgA: This isotype is found in areas of the body such as the gut, respiratory tract, and urogenital tract, and also in saliva, tears, and breast milk. It plays a crucial role in mucosal immunity.

• IgD: This isotype functions mainly as an antigen receptor on B cells that have not been exposed to antigens. It has been shown to activate basophils and mast cells to produce antimicrobial factors.

• IgE: This isotype binds to allergens and triggers histamine release from mast cells and basophils, and is involved in allergy and response to parasitic infections.

• IgG: This isotype is the most common type of antibody found in blood circulation. It provides the majority of antibody-based immunity against invading pathogens.

• IgM: This isotype is expressed on the surface of B cells. It is the first antibody to appear in response to initial exposure to an antigen.

Isotype Switching

Isotype switching, also known as class switch recombination (CSR), is the process by which a B cell changes the production of antibody from one type to another, such as from IgM to IgG, during an immune response. This process allows the immune system to respond to a wide range of infections.

See Also

• Antibody
• Immunoglobulin class switching
• Immunoglobulin G
• Immunoglobulin A
• Immunoglobulin M
• Immunoglobulin E
• Immunoglobulin D

References

Isotype (immunology) Resources
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