Human Autoimmune Diseases Flashcards
How does autoimmunity occur?
Autoimmune responses result from failures of tolerance. They are typically associated with chronic immunopathologies because targeted self-antigens are not eliminated.
How are autoimmunities categorized?
In terms of type II, III and IV hypersensitivity effector mechanisms. Further categorized as systemic or organ specific
Categorize and describe autoimmune hemolytic anemia
Type II, systemic. Abs bind to RBC surface Ags, killing the RBCs by phagocytosis or complement-mediated lysis
Categorize and describe Grave’s disease
Type II, organ-specific: thyroid gland. Autoantibodies to TSH receptors, which leads to overproduction of thyroid hormones.
Categorize and describe Hashimoto’s disease
Type II and type IV, organ-specific: thyroid gland. Autoreactive T & B cells progressively destroy thyroid tissue, causing a decreased ability to make thyroid hormones
Categorize and describe insulin dependent diabetes mellitus (IDDM)
Type II and IV, organ-specific: pancreatic islet cells. Abs and T cells attack and destroy islet cells causing inability to produce insulin and therefore inability to metabolize glucose. Tx: lifetime glucose monitoring & insulin injections
Categorize and describe systemic lupus erythematosus (SLE)
Type III, systemic. Abs against self nuclear proteins and other ubiquitous self proteins, which leads to immune complex deposition and type III hypersensitivity. SS: butterfly shaped facial rash. Most susceptible: women of African and Asian descent
Categorize and describe rheumatoid arthritis (RA)
Type III and IV, systemic. Immune response to Ags in connective tissue and against own IgG antibodies. Anti-IgG antibodies = rheumatoid factors, which are found in ~80% RA patients. SS: chronic inflammation in joints, painful and can lead to loss of fxn
Categorize and describe myasthenia gravis
Type II, systemic: neuromuscular system. Autoantibodies attack acetylcholine receptors (thus are anti-acetylcholine receptor antibodies), blocking the nerve cell’s ability to stimulate muscle contractions, which leads to progressive muscular weakening.
Categorize and describe multiple sclerosis
Type IV, CNS and systemic. Destruction of myelin sheath of CNS axons leading to progressive paralysis.
Explain autoimmunity in terms of hypersensitivities
The immune system produces antibodies to self (endogenous) antigens, which lead to different types of hypersensitivities
Describe the mechanisms of each autoimmune hypersensitivity type
Type II: Autoantibody-coated cells activate the complement system, resulting in tissue injury.
Type III: antibody-antigen (immune) complexes are deposited and not cleared leading to inflammation
Type IV: Injury is T-cell-mediated
