Immune complex

Definition

An immune complex is a structure formed when an antibody binds to its specific antigen. These complexes can trigger inflammation and tissue damage if not properly cleared from the body.

5 Must Know Facts For Your Next Test

1. Immune complexes are central to Type III hypersensitivity reactions, which involve immune complex-mediated tissue injury.
2. Conditions such as systemic lupus erythematosus (SLE) and rheumatoid arthritis involve pathological immune complex formation.
3. The size of the immune complex influences its clearance; smaller complexes can deposit in tissues causing damage, while larger ones are more easily removed by phagocytes.
4. Persistent immune complexes can lead to chronic inflammatory diseases due to continuous activation of the complement system.
5. Laboratory tests like immunofluorescence and ELISA can detect circulating immune complexes in patients.

Review Questions

• What role do immune complexes play in Type III hypersensitivity reactions?
• How does the size of an immune complex affect its clearance from the body?
• Which autoimmune disorders are commonly associated with harmful immune complex formation?

Related terms

Antigen: A molecule or molecular structure that can be bound by an antibody or an antigen receptor on B cells or T cells.

Antibody: A large Y-shaped protein produced mainly by plasma cells that is used by the immune system to neutralize pathogens such as bacteria and viruses.

Complement System: A part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promotes inflammation, and attacks the pathogen's cell membrane.