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Insulin-dependent diabetes mellitus (IDDM)
- an example of type IV hypersensitivity
-T cells invade the pancreatic islets & destroy the insulin secreting beta cells
- Antibody against beta cells and their components are produced at the beginning of the disease and are sometimes useful in diagnosis
- HLA genes are involved at some degree
- Environmental factors are important (infection)
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Celiac Disease
- an auto immune disease in which lymphocytes and macrophages infiltrate the jejunum.
- Type IV hypersensitivity against an exogenous antigen, gliadin (Wheat, rye and barley contain a protein called, gluten, which in turn contains a polypeptide, giadin), and an auto-antigen, tissue transglutaminase (an enzyme that converts the amino acid glutamine to glutamic acid)
-HLA genes are important factor
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Autoimmune Hemolysis anemia (AIHA)
- AIHA can be triggered by infection or drugs( type II hypersensitivity) or can be a part of generalized autoimmune disease such as systemic lupus erythematosus.
-Red cells antigens can become targets for IgG and IgM autoantibodies.
- -IgM antibodies often bind red cells best at temperatures below 37C.
- These cold antibodies can cause red cells (or neurophils) to aggregate in vessels in the hand and fet, and may cause damage. Exposure to cold causes redness due to lysis of RBCs.
-IgG antibodies (warm antibodies ) can bind to red cells best at body temp (37C)
-Diagnosis - Coombs ' test is used to determine when cells are coated with antibody.
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Graves' disease
- Most common with hyperthyroidism, often affect young women with family history
-linked to the HLA gene
-Thyroid is stimulated by an autoantibody that bind onto the thyroid - stimulating hormone receptor on cells (type II hypersensitivity)
-Associated with exophthalmos (protruding eyes) resulting from T cells infiltrating the orbit of the eye
-In Hashimoto Thyroiditis, both auto-antibodies and T cells are reactive to the thyroid gland, but in this they reduce the level of thyroxin by destroying follicle cells and by inactivating the hormone (hypothyroidism)
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Wegner's granolulomatosis
- a RARE disease, a type of blood vessel inflammation (vaculitis) affecting the nose, lung and glomeruli
- Autoantibodies produced to react with proteinase 3, a proteolytic enzyme present in neurophil. These antibodies referred to as classical anti-neurophil cytoplasmic antibodies (cANCA) and they produce a typical indirect immunofluorescence pattern.
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factors affecting the immune system
- 1. age
- 2. nutrition
- 3. smoking
- 4. drug abuse
- 5. chronic disease
- 6. stress
- 7. pregnancy
- 8. preexisting infections
- 9. genetics
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