Immune tolerance
Immune or immunological tolerance is the process by which the immune system does not attack an antigen. It occurs in three forms: central tolerance, peripheral tolerance and acquired tolerance.
Central tolerance
Central tolerance is immunological tolerance developed during T and B cell differentiation.
Peripheral tolerance
Peripheral tolerance is immunological tolerance developed after T and B cells mature and enter the periphery.
Acquired tolerance
Acquired or induced tolerance is the immune system's tolerance for external antigens. One of the most important natural kinds of acquired tolerance occurs during pregnancy where the fetus must be tolerated by the maternal immune system. One model for the induction of tolerance during the very early stages of pregnancy is the eutherian fetoembryonic defense system (eu-FEDS) hypothesis[1]. . However, another model suggests that the induction of tolerance primarily requires the participation of regulatory T cells[2]. In clinical practice, acquired immunity is important in organ transplantation, when the body must be forced to accept an organ from another individual. The failure of the body to accept an organ is known as transplant rejection. To prevent rejection, a variety of medicines are used to produce induced tolerance.
A form of acquired tolerance is oral tolerance[3]. Oral tolerance is the body's tolerance for its own antigens and proteins, such as food taken into the body by mouth. Failure of oral tolerance is attributed to the development and pathogenesis of Inflammatory Bowel Disease (Crohn's Disease and Ulcerative Colitis).
References
- ^ Clark, Clark G.F., Dell A., Morris H.R., Patankar M.S., and Easton R.L. (2001) The species recognition system: a new corollary to the human fetoembryonic defense system hypothesis. Cells Tissues Organs 168, 113-21 PMID 11114593
- ^ Trowsdale J, and Betz AG. 2006. Mother's little helpers: mechanisms of maternal-fetal tolerance. Nature Reviews Immunology 7:241-6 PMID 16482172
- ^ Lloyd Mayer, Kirk Sperber, Lisa Chan, Joseph Child, Lisa Toy (2001) Oral tolerance to protein antigens Allergy 56 (s67), 12–15. doi:10.1111/j.1398-9995.2001.00904.x
See also
External links
| Immune system / Immunology | |
|---|---|
| Systems | Adaptive immune system vs. Innate immune system • Humoral immune system vs. Cellular immune system • Complement system (Anaphylatoxins) |
| Antibodies and antigens | |
| Immune cells | White blood cells
(T cell, |
| Immunity vs. tolerance | Immunity • Autoimmunity • Allergy • Tolerance (Central) • Immunodeficiency |
| Immunogenetics | Somatic
hypermutation • V(D)J recombination • Immunoglobulin class switching • |
| Other | Cytokines • Inflammation • Opsonin |
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