Autoimmunity and Autoimmune Diseases Flashcards
What are the major categories that cause development of autoimmune disease?
immunologic factors, genetic factors, hormonal factors, environmental factors
Explain the “2-hit” mechanism.
a combination of defects of immunoregulation and an environmental triggers in a genetically susceptible individual
How do immunologic factors lead to autoimmune system?
breaking tolerance, whether the disease is caused by inflammatory T cells or antibody
What are some possible mechanisms of immunologic factors?
defects in clonal deletion of self-reactive B cells that does not eliminate all autoreactive B cells
lack of T cell help is another mechanism controlling B cell activation (T cell help may be provided
B cell anergy, may occur after encounter with soluble self-antigen
T cell deletion during development in the thymus may be incomplete if a self-antigen is not expressed in the thymus or defects in AIRE allowing autoreactive cells to escape into the periphery
clonal anergy may not be effective or may be overcome if T cell co-stimulation is inappropriate
clonal ignorance may fail due to release of sequester of antigens or increased of antigens
How would genetic factors affect the development of autoimmune diseases?
account for susceptibility among families
What are some genetic causes of autoimmune diseases?
genes located in the MHC region, variants of complement, variants of CTLA-4, variants of AIRE, variants of Fas and Fas ligand
What are the hormonal factors that cause autoimmune diseases?
Occur in a higher incidence in women than men; estrogen seems to play a roll by exacerbating the disease; substances that behave like estrogen also play a role in autoimmune diseases
What are the environmental factors that may be linked to the development of autoimmunity?
alteration of the structure of self antigens by drugs
chemicals and metals in the environment have been linked to autoimmunity
breakdown of tissue integrity due to trauma
loss of oral tolerance to food proteins
infections may contribute to disease
How might infection contribute to disease?
molecular mimicry–>proteins from the microbe contain sequences that are found in self-antigens
bystander effect, due to the production of high levels of interferon gamma
damage to tissue releases self antigens
What are the classifications of autoimmune diseases?
may be classified as organ-specific if only one organ or cell type is involved or systemic if multiple organs are involved
what is another method of classifying autoimmune disease?
immunological effector mechanism causing disease
what are antibody-mediated autoimmune disease?
a single type of cell is targeted by autoantibodies; organ-specific; Type II hypersensitivity
What are some examples of anti-body mediated autoimmune diseases
autoimmune hemolytic anemia autoimmune thrombocytopenia Goodpasture's syndrome Grave's disease Myasthenia gravis Insulin resistant diabetes hasimoto's disease
is it possible for neonates to see some temporary symptoms of antibody mediated diseases
yes
What are the immune complex mediated autoimmune diseases?
multiple cells of the body, resulting in a systemic autoimmune response; effector mechanisms correspond to type III hypersensitivity reactions
