====== Immunological tolerance ======

Immunological tolerance is the ability of an individual's immune system to ignore "self" while reacting to "non-self" organisms and substances.

The system is extremely complex, and needs to somehow set a balance between being able to accurately sense and eradicate "non-self" entities, whilst leaving the "self" cells etc. untouched.

Malfunctions of the system, in which it over-sensitively targets "self" structures, are believed to be of profound importance with autoimmune diseases such as [[content:medicine:diseases:r-z:rheumatoid_arthritis]] and [[content:medicine:diseases:g-l:lupus]] etc.

The mechanisms by which immunological tolerance is maintained in balance (and how it sometimes goes out of balance) are unclear. There are currently five main theories which attempt an explanation . They are the :

  * Clonal deletion theory
  * Clonal anergy theory
  * Idiotype network theory
  * Clonal ignorance theory
  * Suppressor population theory

For details, see: [[https://en.wikipedia.org/wiki/Autoimmunity#Immunological_tolerance|Wikipedia]]

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Also see [[content:life_sciences:human_body:foetal_immunity]]

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