What is autoimmune ..
Autoimmunity causes number of diseases. that are caused by
the body's own immune system getting confused and wrongly
attacking the body's good cells. Which autoimmune diseases occur
from the immune confusion depends on which body cells are
mistakenly attacked. They total over a hundred
diseases. Some of the best known diseases that are believed to be
autoimmune include thyroditis, juvenile diabetes, lupus, celiac
disease, multiple sclerosis, and C.I.D.P.
Prevalence of autoimmune diseases in the population may be 8%
Features of Autoimmunity
Some important features of the various autoimmune diseases as a category include:
- Cell death: The underlying cause of the disease is damage to cells, usually a particular type of cell. Different cells are attacked in each autoimmune disease.
- Young people's disease: elderly people get autoimmune diseases. It general its a syndrome of young adults and children and old people. Surprisingly, however, the elderly have a much higher level of autoantibodies, and get less AI diseases in general.
- Non-neonatal disease: AI does occur in neonatal infants, at least till around 6 months, it becomes more prominent when diseases such as Type 1 diabetes are not unknown. This delay presumably is because neonatal immune systems are not formed. (Or maybe mother's passive immunity from placenta and breast feeding affects this?)
- Women targeted: although not all autoimmune diseases show gender bias, the overall ratio for all autoimmune cases is almost 3-1 on the side of women over men, with around 75% of AI diseases occurring in women. AI diseases have been reported as in the top ten causes of women under 65. What is the role of the hormonal flux from women's reproductive systems and its effect on AI diseases? Interestingly, women were once more likely to get cancer, until the environmental effects of male smoking and occupational hazards raised male risks. Many different AI diseases have a strong female gender bias. As the exceptions, there is no gender bias in Type 1 diabetes or autoimmune myocarditis.
- Trigger suspects: the possible suspects for what triggers the start of an autoimmune disease are many, but include: viruses, bacteria, diet, toxins, radiation, chronic infections, vaccination, accidents, trauma, stress, surgery.
- Risk factors: genetics (significant but not total), immune system abnormalities. Exposure to chemicals which makes the expression of genes weaker.
- Non genetic: although there are some inherited sub-types, and some inheritance factors in all autoimmune disease, autoimmunity is "polygenic" (from many genes) and has an unclear inheritance pattern. Risks to children and siblings of an infected person are higher but not as high as for a true genetic disease. For example, probably only around 4-6% chance for a Type 1 diabetic to pass the disease to their child.
- Not contagious: autoimmunity cannot be passed by fluids or blood under normal circumstances. Some autoimmune diseases have been transferred between animals by the careful transfer of immune system cells. Even this is not dangerous for most healthy animals, and only works for special immune-suppressed animal strains.
- Cross-placental contagion: There are cases of mothers giving their unborn children an autoimmune disease, including Myasthenia Gravis and Grave's disease (thyroid). This is not common, but can occur.
- Organ-specific or systemic: Some autoimmune diseases like Type 1 diabetes are specific to a particular organ (pancreas cells). Other autoimmune diseases like SLE and RA are systemic to multiple body organs. This seems to depend on what type of cell the disease attacks. Pancreas cells attacked by diabetes are not present in any other body organs, whereas collagen that is attacked by RA is present in many places in the body.
- Degenerative or fluctuating with remissions: Some diseases degenerate to a final state, where all cells are dead, such as Type 1 diabetes where all insulin-producing cells die over time. Other autoimmune diseases seem to fluctuate, such as MS, SLE and RA, and have long periods of remission. (Why is this? These diseases have more of the type of cells?)
- Immune involvement: There are several aspects that show that the immune system is involved in most autoimmune diseases. These include the presence of antibodies in the blood and immune infection features near or within the attacked cells themselves (i.e. lots of immune cells).
- Antibodies present: Many autoimmune diseases are characterized by the presence of a particular disease-specific antibody. This is especially true of organ-specific diseases such as Type 1 diabetes, which has antibodies against pancreas islet cells (ICA antibodies) and the anti-GAD protein antibodies. Systemic autoimmune diseases such as SLE may have less specific antibodies, but there is a strong association with anti-nuclear antibodies (ANAs).
- Multiple antibodies: A common feature of some autoimmune diseases is that there are multiple antibodies against different cells in the same organ. For example, Type 1 diabetes involves some combination of insulin autoantibodies (IAA), islet cell antibody (ICA) and GAD antibodies. Does one antibody start the situation and cause the others, or are all antibodies needed for disease?
Causes of Autoimmune Disease
Autoimmunity as a theory states that the immune system itself gets tricked into killing good normal cells. The immune system wrongly makes antibodies to normal cells, which cause these cells to be attacked and killed, just as if they were recognized as unhealthy virus-infected cells. The key questions about the cause of autoimmune diseases are:
- Triggers: what starts the immune system on the wrong path?
- Conversion: what causes the immune system to respond to the trigger?
- Progression: what makes the immune system keep on with the autoimmune response?
In the prevailing theories about triggers of autoimmune diseases, the trigger does not necessarily need to stay around. For example, a viral infection may trigger the immune response, but the virus need not stay as a chronic infection for the person to develop autoimmunity.