Immunoglobulin

Immunoglobulin (also known as Ig) is a type of protein produced by plasma cells and other lymphocytes. Certain types of immunoglobulins are also known as antibodies. Immunoglobulins play a key role in the immune system by recognizing and binding to specific antigens, such as bacteria or viruses, and aiding in their destruction.

Types of Immunoglobulins

There are five classes of immunoglobulins, each with a different role in the immune response. These include:

• Immunoglobulin G (IgG): This is the most common type of immunoglobulin. It protects against bacterial and viral infections.

• Immunoglobulin A (IgA): Found in high concentrations in the mucous membranes, particularly those lining the respiratory passages and gastrointestinal tract, as well as in saliva and tears.

• Immunoglobulin M (IgM): The first immunoglobulin produced in response to an infection. It also causes other immune system cells to destroy the pathogen.

• Immunoglobulin E (IgE): Binds to allergens and triggers histamine release from mast cells and basophils, and is involved in allergy.

• Immunoglobulin D (IgD): Functions mainly as an antigen receptor on B cells that have not been exposed to antigens.

Function of Immunoglobulins

Immunoglobulins have two primary functions:

• Antigen binding: Immunoglobulins recognize specific antigens and bind to them. This binding can neutralize the antigen or make it easier for other cells of the immune system to destroy the antigen.

• Effector function: After binding to an antigen, the Fc region of the immunoglobulin can interact with immune cells and complement proteins, triggering a range of immune responses.

Clinical Significance

Immunoglobulins are crucial for our body's defence against microorganisms. Abnormal immunoglobulin levels can be a sign of a health problem. These may include:

• Immunodeficiency: Lower than normal levels of immunoglobulins can lead to repeated infections.

• Autoimmune diseases: In some cases, immunoglobulins might mistakenly target the body's own cells, causing an autoimmune disease.

• Allergies: High levels of a specific type of immunoglobulin known as IgE might indicate an allergy.

• Cancers: Certain cancers, such as multiple myeloma, can cause a spike in the levels of a specific type of immunoglobulin.

Immunoglobulin Resources
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