Immuno 17 Flashcards
What is autoimmunity?
immune response directed at “self” tissues/antigens
What is an antagonist?
an antibody that binds to cell surface receptor, thereby preventing it’s function
What is an agonist?
An antibody that binds to a cell surface receptor in a way that mimics the binding of the actual ligand to the receptor
How do autoimmune diseases arise?
Thru a breakdown of neg. selection processes that remove self-reactive B and T cells from the lymphocyte repertoire.
What percentage of people experience autoimmune diseases in developed countries?
2-3%
Are autoimmume diseases ever mediated by IgE antibodies?
No
What are type II autoimmune diseases?
Caused by Abs specific for components of cell surfaces or the extracellular matrix
What is Autoimmune Hemolytic Anemia?
IgG and IgM bind to the surface of erythrocytes, activating the complement cascade, destroying the RBCs.
What is neutropenia?
The WBCs can be targets, specifically neutrophils, causing a reduced number of circulating neutrophils. A common treatment is splenectomy, which reduces the amount of destroyed blood cells.
What is Goodpasture’s Syndrome?
Antibodies are specific for extracellular matrix autoantigens, specifically those associated with the alpha chain of type IV collagen. As such, Abs are deposited along basement membranes of renal glomeruli and renal tubules, eliciting an inflammatory response.
What are the consequences of Goodpasture’s Syndrome?
Impaired kidney function, and eventual kidney failure.
How do you treat Goodpasture’s Syndrome?
plasma exchange to remove self-reactive Abs, and immunosuppressant drugs to prevent production of new Abs.
What is Acute Rheumatic Fever?
Caused by Abs which are produced in response to bacterial infxn that cross-react with self-antigens of the human heart. Due to similarities between strep cell walls and heart muscle.
What is Grave’s disease?
Caused by Abs that bind to thyroid stimulatory hormone receptor, mimicking TSH.
What are the symptoms of Grave’s disease?
Heat intolerance, nervousness, irritability, warm moist skin, weight loss, bulging eyes, stare.
How do you treat Grave’s disease?
Drugs to reduce thyroid activity or removal of thyroid.
What autoimmune diseases will be passed on to the fetus? Why?
Goodpasture’s and Graves because both are mediated by IgG, which crosses the placenta
What is myasthenia gravis?
Autoimmune disease in which signaling from nerve to muscle across neuromuscular junction is impaired.
What is the mechanism of Myasthenia Gravis?
Autoantibodies specific for Ach receptors on muscle cells bind to receptors, inducing their endocytosis and degradation. Thus, leaves the muslce less sensitive to neuronal stimulation
How do you treat Myasthenia Gravis?
Immunosuppressive drugs or pyridostigmine, which inhibits cholinesterase (which degrades Ach)
What is the first sign of myasthenia gravis?
Paralyzed facial muscles, esp eyes.
What is Guillain Barre Syndrome?
Mediated by IgG specific for human nerve tissue (gangliosides) which mediate acute inflammatory demyelinating polyneuropathy. Symmetrical weakness of lower limb, then upper limbs and face. Regain most funxn with treatment
What infection commonly leads to GBS?
Camplyobacter jejuni
What is Wegener’s Granulomatosis?
Type II autoimmune disease mediated by anti-neutrophil Abs or IgG. ANCAs bind to neutrophils, causing activation. Then they upregulate adhesin mculs, allowing binding to endothelial cells and then degranulate causing granulitis.
What is a type III autoimmune disease?
Caused by immune complexes that are deposite in tissues
What is SLE?
Systemic Lupu Erthematosus - AI disease caused by Autoantibodies specific for many intracellular macromolecules present in all cells in the body (DNA, histones, ribosomes). Autoantibodies bind to cell surface components, triggering inflammatory responses leading to tissue destruction. Autoabs then bind to released molecules, forming soluble entities that deposit into the joints and other tissues
What do most patients die of that have SLE?
Tissue or organ failure due to the immune-regulated inflammatory response
What are Type IV Autoimmune diseases?
T cell-mediated autoimmune disease
What is insulin-dependent diabetes mellitus?
AI disease that results in selective destruction of insulin-producing beta cells in the pancreas
How do you treat IDDM?
Daily injections of pig insulin or cattle
What is rheumatoid arthritis?
Autoimmune disease that results in inflammation of the joints.
What are rheumatoid factors?
IgM, IgG and IgA that are specific for the Fc region of IgG mculs.
What is commonly found in joints of those with rheumatoid arthritis?
Leukocytes including CD4 and CD8 T cells, B cells, plasma cells, neutrophils, and macrophages.
What are two drugs used to treat rheumatoid arthritis?
infliximab - a TNF-alpha blocker
rutiximab - monoclonal abs that bind to B cells, attracting NK cells to kill them via ADCC
What is multiple sclerosis?
Targeting myelin sheaths of nerve cells, causes sclerotic plaques of demyelinated tissue in white matter of CNS.
What cells are responsible for the demyelination in MS?
Activated Th1 CD4 cells, which produce IFN-gamma that activates macrophages causing demyelination
What are treatments for MS?
immunosuppressive drugs and subq injections of IFN-beta1.
What is sjogrens syndrome?
A t-cell mediated disease that attacks exocrine glands that produce tears and saliva and lubricative substances.
What is a genetic expression factor that frequently is more common in those with AI diseases?
Expression of certain HLA allotypes, such as HLA-DR2 in Goodpasture’s Syndrome
What is molecular mimicry?
When an organism produces a protein that is very similar to self-proteins, or contain antigens that closely mimic self components.
