Autoimmune responses involve immune responses directed at self, and are operative in the development of immunological tolerance to self. Autoimmune diseases arise when the immune system targets the organism's tissues because of a failure of tolerance.

Several hypotheses have been proposed to explain mechanisms of immumological tolerance:
● Clonal Deletion theory – proposal that self-reactive lymphoid cells are destroyed during the development of the immune system in an individual.
Clonal Anergy theory – proposal that self-reactive T- or B-cells become inactivated in the normal individual and cannot amplify the immune response.
● Idiotype Network theory – proposal that a network of antibodies capable of neutralising self-reactive antibodies exists naturally within the body.
● Suppressor population or Regulatory T cell theories – proposal that regulatory T-lymphocytes (commonly including CD4+FoxP3+ cells) function to prevent, downregulate, or limit autoaggressive immune responses.
● Clonal Ignorance theory – proposal that host immune responses are directed to ignore self-antigens

Tables  Fc receptors  Immune Cytokines  Immunoglobulins  Cell Adhesion Molecules  Cell signaling  Receptor Tyrosine Kinases (RTKs)  Receptor Signal Transduction  Second Messengers 


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. . . since 10/06/06