CD35

Definition

CD35, also known as complement receptor 1 (CR1), is a protein found on the surface of various immune cells that plays a vital role in the immune response by facilitating the clearance of immune complexes and pathogens. It acts by binding to complement proteins, specifically C3b and C4b, enhancing phagocytosis and promoting opsonization, which is essential for effective immunity.

5 Must Know Facts For Your Next Test

1. CD35 is expressed on various cell types, including erythrocytes, macrophages, and B cells, playing a crucial role in regulating the immune response.
2. It functions as a receptor for complement proteins, allowing immune cells to recognize and bind to pathogens that have been tagged with complement components.
3. CD35 is involved in downregulating the complement activation process to prevent excessive inflammation and tissue damage during an immune response.
4. The interaction between CD35 and complement components enhances the efficiency of phagocytosis, aiding in the removal of pathogens from circulation.
5. Deficiencies or dysfunctions in CD35 can lead to increased susceptibility to infections due to impaired clearance of immune complexes and pathogens.

Review Questions

• How does CD35 contribute to the process of opsonization and phagocytosis in the immune response?
  • CD35 enhances opsonization by binding to complement proteins like C3b that coat pathogens. This binding facilitates recognition by phagocytic cells, promoting their engulfment and destruction. As a result, CD35 plays a critical role in linking the complement system to effective immune responses.
• In what ways does CD35 regulate the complement activation process to prevent tissue damage?
  • CD35 helps regulate the complement activation process by mediating the clearance of activated complement components from circulation. By binding to C3b and C4b, CD35 promotes their decay and prevents excessive accumulation that could lead to uncontrolled inflammation and potential tissue damage. This regulatory function is essential for maintaining homeostasis during immune responses.
• Evaluate the implications of CD35 deficiencies on an individual’s susceptibility to infections.
  • Deficiencies in CD35 can significantly impact an individual's ability to clear pathogens and immune complexes effectively. Without sufficient CD35 function, there may be an accumulation of unopsonized pathogens, leading to a heightened risk of infections. Additionally, such deficiencies can result in chronic inflammation due to ineffective regulation of complement activation, further compromising immune health and increasing susceptibility to various infectious diseases.

Related terms

Complement System: A group of proteins in the blood that work together to enhance the ability of antibodies and phagocytic cells to clear pathogens from an organism.

Opsonization:

The process by which pathogens are marked for ingestion and destruction by phagocytes, often facilitated by the binding of antibodies or complement proteins.

Phagocytosis:

The process by which certain cells, known as phagocytes, engulf and digest foreign particles, including bacteria and dead or dying cells.