What are the classes of antibodies?
1. Immunoglobulin G (IgG):
- Most abundant class of antibodies
- Found in blood and other body fluids
- Can cross the placenta, providing protection to the fetus
- Involved in secondary immune responses and long-term immunity
- Activates the complement system, enhancing immune defenses
2. Immunoglobulin A (IgA):
- Found in saliva, tears, breast milk, and other mucosal secretions
- Protects mucosal surfaces from infections
- Can cross the placenta, but in lower amounts compared to IgG
- Plays a role in local immunity
3. Immunoglobulin M (IgM):
- First antibody produced in response to an infection
- Involved in primary immune responses
- Found in high concentrations in blood early during an infection
- Has a large molecular size and is efficient in activating the complement system
4. Immunoglobulin D (IgD):
- Found on the surface of B cells
- Acts as a receptor for antigens on B cells, triggering B cell activation and antibody production
- Involved in regulating immune responses
5. Immunoglobulin E (IgE):
- Found on the surface of mast cells and basophils
- Binds to allergens and triggers the release of histamine and other inflammatory mediators
- Involved in allergic reactions and anaphylaxis
Each antibody class has distinct properties and functions that enable the immune system to effectively recognize and respond to various pathogens and antigens.