Immunoglobulin M

Immunoglobulin M

Immunoglobulin M (IgM) is one of the several forms of antibody that are produced by the immune system in response to an infection. It is the first antibody to be produced in response to an initial exposure to an antigen.

Structure

IgM is a large molecule, consisting of five or six monomer units that are each composed of two heavy chains and two light chains. These monomers are arranged in a pentameric or hexameric structure, forming a complex with a molecular weight of approximately 900,000 Daltons.

Function

IgM plays a crucial role in the immune response. It is the first antibody to be produced following exposure to an antigen, and it initiates the complement system, a series of proteins that work together to destroy invading pathogens. IgM also binds to and agglutinates pathogens, making them easier for phagocytes to engulf and destroy.

Clinical significance

Abnormal levels of IgM can indicate a variety of medical conditions. High levels of IgM may indicate a recent infection, an autoimmune disease, or certain types of cancer. Low levels of IgM can indicate a weakened immune system, which may be due to a variety of causes including certain genetic disorders, malnutrition, or HIV/AIDS.

See also

• Immunoglobulin
• Antibody
• Immune system
• Antigen
• Complement system
• Phagocyte
• Autoimmune disease
• Cancer
• Genetic disorder
• Malnutrition
• HIV/AIDS