Immune complex

An immune complex is a molecule formed from the binding of multiple antibodies to antigens. These complexes play a crucial role in the immune system by facilitating the removal of antigens from the body. However, they can also contribute to the pathogenesis of various immune complex diseases.

Diagram of an immune complex formation

Formation

Immune complexes are formed when antibodies, which are proteins produced by B cells, bind to specific antigens. This binding is a key part of the adaptive immune response, allowing the body to target and neutralize foreign pathogens such as bacteria and viruses.

Function

The primary function of immune complexes is to facilitate the clearance of antigens. Once formed, these complexes can activate the complement system, a group of proteins that assists in the destruction of pathogens. The complement system enhances the ability of phagocytes to engulf and destroy antigens, a process known as opsonization.

Pathological Effects

While immune complexes are essential for normal immune function, their accumulation can lead to immune complex-mediated diseases. These diseases occur when immune complexes deposit in tissues, causing inflammation and tissue damage. Examples include:

• Systemic lupus erythematosus
• Rheumatoid arthritis
• Glomerulonephritis

Clearance

The body has mechanisms to clear immune complexes from the circulation. Macrophages and other phagocytic cells in the reticuloendothelial system play a significant role in this process. Additionally, the spleen and liver are involved in filtering and removing these complexes.

Related Pages

• Antibody
• Antigen
• Complement system
• Phagocytosis
• Autoimmune disease