How do immune complexes cause disease?
Immune complexes may cause disease when they are deposited in organs. The Arthus reaction involves the in situ formation of antigen/antibody complexes after the intradermal injection of an antigen (as seen in passive immunity).
What is an immune complex mediated disease?
Immune complex diseases are a group of conditions resulting from inflammation and tissue damage induced in tissues where immune complexes are formed or deposited.
Where are immune complexes formed?
Antigen–antibody complexes are formed when the body’s immune system raises antibodies against antigenic determinants of host or foreign substances that recognise and bind to the antigen molecules.
What happens if immune complexes are not cleared?
Immune complexes must be removed from tissues and kept from accumulating in the circulation and forming deposits throughout the body. Failure to clear immune complexes can lead to autoimmune disease. Complement fixation to immune complexes facilitates their removal by phagocytes.
Why is immune complex formation important?
This allows innate immune cells to get multiple inputs at once and prevents them from being activated early. Immune complexes may themselves cause illness when they are deposited in organs, for example, in certain forms of vasculitis.
What is the pathogenesis of immune complexes?
Immune complexes (type III reaction) are involved in the pathogenesis of vasculitis, serum sickness, some urticarial and exanthematous reactions, systemic lupus erythematosus-like drug reactions, and possibly erythema multiforme and erythema nodosum, when due to drugs.
What is IgG immune complex?
IgG immune complexes are the ligand for these receptors and immune complex binding to these receptors induces apoptosis, or cell death.
What immune cells are stimulated by an antigen antibody complex?
The plasma cells, on the other hand, produce and secrete large quantities, up to 100 million molecules per hour, of antibody molecules. An antibody, also known as an immunoglobulin (Ig), is a protein that is produced by plasma cells after stimulation by an antigen. Antibodies are the agents of humoral immunity.
How do I get rid of immune complexes?
Immune complexes are removed from the circulation by the mononuclear phagocyte system of the liver and spleen through engagement of FcγRs and complement receptors. The interaction of immune complexes with the phagocyte involves a qualitatively different process from that with erythrocytes.
What is a Type 4 hypersensitivity?
Type four hypersensitivity reaction is a cell-mediated reaction that can occur in response to contact with certain allergens resulting in what is called contact dermatitis or in response to some diagnostic procedures as in the tuberculin skin test. Certain allergens must be avoided to treat this condition.
Is SLE Type 4 hypersensitivity?
SLE is a prototype type III hypersensitivity reaction. Local deposition of anti-nuclear antibodies in complex with released chromatin induces serious inflammatory conditions by activation of the complement system.
Do B cells produce IgG?
Immunoglobulin G (IgG) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells.
What is the role played by IgG in providing immunity?
IgG antibodies are usually of higher affinity and are found in blood and in extracellular fluid, where they can neutralize toxins, viruses, and bacteria, opsonize them for phagocytosis, and activate the complement system.