A lot more IVIG is used for the treatment of autoimmune and inflammatory disorders than as replacement therapy in patients with immune deficiency.
A number of mechanisms for the immune modulation and anti-inflammatory actions of IVIG have been described:
- Fc receptor blockade
- inhibition of complement deposition
- enhancement of regulatory T cells (T regs)
- inhibition or neutralization of cytokines and growth factors
- accelerated clearance of autoantibodies
- modulation of adhesion molecules and cell receptors
- activation of regulatory macrophages through the FcγRIIb receptor
An antibody has Fab (fragment, antigen-binding) and Fc (fragment, crystalizable) regions. Fc receptors bind to the Fc region. Image source: Wikipedia, public domain.
Fc receptor interaction with an antibody-coated microbial pathogen. Image source: Wikipedia, public domain.
IVIG affects many different pathways to modulate the immune and inflammatory response.
The IgG molecule as a biological immune response modifier: Mechanisms of action of intravenous immune serum globulin in autoimmune and inflammatory disorders. Ballow M. J Allergy Clin Immunol. 2010 Dec 23.
Image source: OpenClipArt.org, public domain.