Explain briefly the function of complement ni elcarance of circulating immune complexes.

Sourav PanSeptember 4, 2024

Answered

Complement plays a crucial role in the clearance of circulating immune complexes through a process known as complement-mediated clearance. Here’s a brief explanation of how this works:

Function of Complement in Clearance of Immune Complexes

1. Formation of Immune Complexes:
   • Immune complexes are formed when antibodies bind to antigens, creating a complex of antibody-antigen pairs.
2. Activation of Complement:
   • When immune complexes enter the bloodstream, they can activate the complement system, particularly the classical pathway. This activation leads to the generation of complement proteins and fragments that bind to the immune complexes.
3. Opsonization:
   • Complement proteins, such as C3b, bind to the immune complexes. This process is known as opsonization. Complement binding enhances the recognition and uptake of immune complexes by phagocytic cells.
4. Phagocytosis:
   • Phagocytic cells, such as macrophages and neutrophils, have receptors for complement fragments (e.g., C3b receptors). These cells bind to the opsonized immune complexes and engulf them through phagocytosis.
5. Clearance from Circulation:
   • After phagocytosis, the immune complexes are degraded within the phagocytes. This process helps to remove immune complexes from the bloodstream and tissues, preventing their accumulation and potential damage.

Summary

• Complement Activation: Leads to binding of complement proteins to immune complexes.
• Opsonization: Complement-coated immune complexes are more readily recognized by phagocytes.
• Phagocytosis: Phagocytes engulf and digest the immune complexes.
• Clearing: The immune complexes are removed from circulation and broken down, reducing potential tissue damage and maintaining immune system balance.