Circulating immune complexes

Circulating Immune Complexes (CICs) are a fundamental part of the immune system's response to foreign antigens. They are formed when antibodies bind to antigens, creating complexes that circulate in the bloodstream. These complexes are typically removed from circulation by phagocytic cells, but in certain conditions, they can accumulate and cause disease.

Formation and Function

Circulating immune complexes are formed during the immune response to an antigen. When an antigen-presenting cell encounters an antigen, it presents fragments of the antigen to T cells, which then stimulate B cells to produce antibodies. These antibodies bind to the antigen, forming an immune complex.

The primary function of circulating immune complexes is to facilitate the removal of antigens from the body. The complexes are recognized by Fc receptors on phagocytic cells, which engulf and destroy the complex, effectively removing the antigen.

Role in Disease

In certain conditions, circulating immune complexes can accumulate in the body and cause disease. This is often due to an overproduction of antibodies, an inability to clear the complexes, or a combination of both. The accumulation of these complexes can lead to a variety of diseases, collectively known as immune complex diseases.

One of the most well-known immune complex diseases is Systemic Lupus Erythematosus (SLE), a chronic autoimmune disease in which the body's immune system mistakenly attacks healthy tissue. In SLE, circulating immune complexes deposit in various tissues, causing inflammation and damage.

Detection and Measurement

The detection and measurement of circulating immune complexes can be useful in the diagnosis and monitoring of immune complex diseases. Several methods are available for this purpose, including the C1q binding assay, Polyethylene glycol precipitation, and Enzyme-linked immunosorbent assay (ELISA).

See Also

• Antigen
• Antibody
• Immune system
• Immune complex diseases
• Systemic Lupus Erythematosus