IgM

IgM or Immunoglobulin M is one of the several forms of antibody that are produced by the immune system of the body. It is the first antibody to be made by the body to fight a new infection.

Structure

IgM is a macromolecule that is composed of five or six units. Each unit is a Y-shaped structure that is made up of four protein chains: two identical heavy chains and two identical light chains. The heavy chains have a region known as the constant region, which determines the class of an immunoglobulin.

Function

IgM plays a crucial role in humoral immunity, which is the aspect of immunity that is mediated by secreted antibodies. It is the first antibody to appear in response to initial exposure to an antigen. The presence of IgM in the blood is a sign of recent infection, and it also activates the complement system.

Clinical significance

IgM levels in the blood can be measured to give doctors an indication of the body's response to infection. High levels of IgM can indicate a recent infection or exposure to an antigen. Low levels of IgM can indicate a weakened immune system or a deficiency in the production of antibodies.

See also

• Antibody
• Immune system
• Infection
• Antigen
• Complement system
• Humoral immunity

References

IgM Resources
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