Autoimmunity and Autoimmune diseases.
(By--- T.K.MAHATO)
Autoimmunity:----
The presence of autoantibodies (antibodies against
autoantigens)or autoreactive (self reactive)
lymphocytes without the induction of any pathological
changes.
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Autoimmunity and Autoimmune diseases.
(By--- T.K.MAHATO)
Autoimmunity:----
The presence of autoantibodies (antibodies against autoantigens)or autoreactive (self reactive) lymphocytes without the induction of any pathological changes.
Autoantibodies--- Can be found in normal
individuals, particularly in old animals, and in
the female gender group.
Autoantibodies may have a physiological role in:
- Removal of senescent/ damaged cells
- Idiotype anti-idiotypes negative feed back
Criteria for Autoimmune disease or Witebsky’s
postulates.
1. The presence of Autoantibodies or
Autoreactive lymphocytes ( in association with
pathological changes).
2. Experimental reproduction of the
disease in laboratory animals.
3. The features of the
experimental disease must closely match with
the clinical disease.
4. Ability to passively transfer the
disease by Autoantibodies or Lymphocytes.
- Sequestered antigens.
- Defects in the idiotype-anti-idiotype network.
- Genetic factor.
1. Forbidden clones.
Antibody-forming Lymphocytes capable of reacting with different antigens are formed according to clonal selection theory.
Such clones are called Forbidden clones. Their persistence or development in later life by Somatic Mutation can lead to Autoimmunity
- Neoantigens or Altered antigens----- Antigenic alteration result from physical, chemical or biological influences.
(b) Chemical agents----- including drugs can combine with cells and tissues and alter their antigenic structure.
Skin contact with a variety of chemicals may lead to contact dermatitis.
Drug-induced Anemia, Leukopenia and Thrombocytopenia often have Autoimmune basis.
(c) Viruses and other intracellular pathogens------- May induce alterations of cell antigens leading to autoimmunity e,g infectious mononucleosis.
Immunological damage may result from Immune responses induced by cross reacting antigens.
Organ specific antigens are present in several species.
Injections of Heterologous organ specific antigens may induce an immune response damaging the particular organ or tissue in the host.
There may also be Cross-reactivity between HLA-B27 and certain strains of Klebsiella in connection with Ankylosing spondilytis.
Such stimuli include------- Chemicals----, 2-Mercaptoethanol), Bacterial products--- Polypeptides, Lipopolysaccharides.
Enzymes---- Trypsin, Antibiotics----- Nystatin , Infection with some Bacteria----Mycoplasma,
Viruses---- EB virus, CM virus. Parasites -----Malaria.
- Activity of Helper and suppressor T-cells------Enhanced Helper T- cell and decreased suppressor T- cells functions have been suggested as causes of autoimmunity.
- Defects in the Idiotype-Anti-Idiotype network. Abnormalities in the generation of appropriate anti-idiotype antibodies either at the B or T- cell level,
are responsible for the development of autoimmunity in certain circumstances.
- Genetic factors. Genetic factors such as defective Ir or Immunoglobulin genes induces some autoimmune-diseases.