| What is autoimmunity? | ➢ Ehrlich used the term autoimmunity to signify an
immune response against self.
➢ Over the years, autoimmunity has been recognized
as not uncommon and not necessarily detrimental.
➢ All humans have many self-reactive antibodies in
the blood but most show no sign of disease.
➢ Consequently the identification of autoantibodies is
not a sufficient diagnostic tool for determining the
presence of an autoimmune disorder
➢ There is a difference between an autoimmune
response and disease: in the former case the
autoantibodies do not cause dysfunction, but in the
latter case they do.
Autoimmunity may be asx, autoimmune diseases lead to inflammatory response and tissue injury |
| How is epidemiology of autoimmune diseases? | ➢ There are nearly 100 different forms of
autoimmune disease, affecting up to 3 percent of
the general population.
➢ Nearly any organ can be affected by either systemic
or organ-specific autoimmune disease
➢ Women make up nearly 75 percent of all
individuals afflicted by autoimmune disease,
making these disorders one of the ten leading
causes of death in women less than sixty-five years
old. (may be hormonal)
➢ However, the female-to-male ratio varies widely
among different diseases, being as high as 9:1 in
SLE, Sjögren’s syndrome, and autoimmune
thyroiditis and as low as 1:1 in vitiligo, TID, and
Goodpasture’s syndrome
Age of onset: some early childhood, some childbearing age, other later |
| What are some autoimmune diseases? | SLE, RA, Sjogren, Scleroderma, Polymyositis (systemic)
Hashimoto, Graves, Addisons, T1DM, Pemiphigus vulgaris, Bullous pemphigoid, vitiligo, good basture, MG, MS, Pernicious anemia, PBC, autoimmune hep (organ specific) |
| How is pathogenesis of autoimmune diseases? | Genetic, environmental, Immune system malfunction and random factors all play a role in the pathogenesis of autoimmune diseases |
| What are types of autoimmunity? Acc to cell type | T cell (Like MS or AI encephalomyelitis, strength of T cell reactivation deteremines degree of parenchymal inflammation)
B cell (autoantibodies, Like SLE, can be transmitted transplacentally [neonatal Grave's, congentital herat block, neonatal lupus], IgG antibodies cross placenta while IgM don't. half life of IgG 21-28 days so go to baby circulation in 6-12 months postpartum, mostly transient [exception is complete heart block mediated by anti-Ro/anti-La autoantibodies cross reacting w/cardiac antigens causing permenant inflammation and damage]. Usually several mechanisms [T cell and antibody tissue injury] |
| What are types of autoimmunity? Acc to organ affected? | Systemic or organ specific
Systemic (, such as SLE, involve multiple organs or tissues)
Organ-specific ( involve a single organ or tissue, such as the thyroid gland in autoimmune thyroiditis or the islets of Langerhans in type I diabetes (TID)). |
| What are mechanisms of autoimmune tissue injury and examples? | ➢ Tissue damage in autoimmune diseases can occur through several mechanisms, which are analogous to three of the classical types of hypersensitivity reactions:
Type II (caused by autoantibodies reactive with cell surface or matrix antigens),
Type III (caused by immune complexes), and
Type IV (delayed-type hypersensitivity, mediated by T cells).
➢ Autoimmune diseases differ from HS responses in that type I IgE-mediated responses do not seem to have a major role. |
| What are categories of immunopathologic responses? | ◦ Inactivation/activation antibody reactions
◦ Cytotoxic or cytolytic antibody reactions
◦ Immune-complex reactions
◦ Allergic reactions
◦ T-cell cytotoxic reactions
◦ Delayed HS reactions
◦ Granulomatous reactions
➢ This system accounts for the fact that multiple components of the immune system can be involved in various types of HS reactions |
| What is Gell and Coomb's classification of immunopathologic responses? | ➢ Gell and Coomb's classification has deficiencies
but, with mechanism-based categories, it
remains, overall, the simplest, most valid, and
most logical way of distinguishing the host’s
immune sensitivities.
Type I, II, III and IV |
