Tuesday, January 9, 2024

Classes of Antibodies.. IgG (Immunoglobulin G). IgM (Immunoglobulin M). IgA (Immunoglobulin A). IgD (Immunoglobulin D). IgE (Immunoglobulin E)

Classes of Antibodies:

There are five main classes of antibodies (also known as immunoglobulins), each with distinct characteristics and functions:

1. IgG (Immunoglobulin G):

- Most abundant: Makes up about 70-80% of all antibodies in the bloodstream.

- Long half-life:

Can circulate in the blood for weeks or months, providing long-term immunity.

- Neutralizes pathogens:

Can directly bind to and neutralize viruses and bacteria.

- Activates complement system:

Triggers a cascade of immune proteins that further attack and destroy pathogens.

- Crosses placenta:

Can provide passive immunity to a developing fetus.

2. IgM (Immunoglobulin M):

- First-line defense:

First antibody produced in response to a new infection, offering immediate but short-lived immunity.

- Large molecule:

Efficiently binds to pathogens but cannot easily enter tissues.

- Agglutination:

Causes pathogens to clump together, making them easier for phagocytes to engulf.

3. IgA (Immunoglobulin A):

- Present in mucosal secretions:

Found in tears, saliva, breast milk, and respiratory and gastrointestinal secretions, providing protection against mucosal infections.

- Neutralizes toxins and viruses:

Prevents them from attaching to mucosal surfaces.

- Dimers and monomers:

Exists in two forms, monomers for mucosal secretions and dimers for blood circulation.

4. IgD (Immunoglobulin D):

- Least abundant:

Makes up less than 1% of antibodies.

- Role unclear:

Its exact function is not fully understood, but it may be involved in B cell activation and immune memory.

5. IgE (Immunoglobulin E):

- Mediates allergic reactions:

Binds to mast cells and basophils, triggering the release of histamine and other inflammatory chemicals that cause allergic symptoms.

- Defense against parasites:

Also plays a role in defense against certain parasites.

Understanding the different classes of antibodies helps us appreciate the diverse ways our immune system protects us from various types of threats.