Autoimmunity- Miller Flashcards
What is autoimmunity ?
Immune response directed at self antigens
What is an autoimmune response ?
Any immune response that is directed at host tissues, The effectors of the autoimmune response are autoantibodies and autoimmune T cells
What is autoimmune disease ?
Chronic disease state that results from autoimmune responses
What is an antagonist ?
An antibody that binds to a cell surface receptor thereby preventing its function
What is an agonist ?
An Ab that binds to a cell surface receptor in a way that mimics the binding of the actual ligand to the receptor.
How are autoimmune diseases classified ?
By the immunological effector that is responsible for their function
What do autoimmune diseases arise through ?
Through the breakdown of the negative selection processes that remove self-reactive T cells and B cells from the Lymphocyte repertoire
Are autoimmune diseases ever mediated by IgE ?
No, autoimmune diseases are never mediated by IgE antibodies
What causes autoimmune hemolytic anemia ?
When IgG and IgM bind to the surface of erythrocytes
What happens when IgM and IgG bind to an erythrocyte ?
The complement cascade is activated and the RBC is destroyed
RBC depletion results in what condition ?
Anemia
how are RBC’s cleared from circulation?
Bound Ab and Cb3 mediate clearance of RBC’s from circulation by phagocytes in the spleen
How can you confirm Cb3 clearance of RBC’s from the blood ?
Direct Coomb’s Hemagglutination Test
What is neutropenia ?
A decreased number of neutrophils because they have been targeted for destruction by autoimmune responses directed at surface antigens of neutrophils
How can you treat neutropenia ?
Splenectomy will reduce the destruction of WBC’s
What is Type 2 schleroderma ?
Inflammatory destruction of vascuar endothelial cells of arterioles and smooth muscle cells; replacement with collagen and other fibrous materials.
**If can also affect the kidneys blood vessels, liver, and brain
What are the symptoms of Schleroderma ?
Localized or symmetrical skin thickening; hard smooth ivory colored areas of hardened skin
What is required to diagnose schleroderma
presence of anti-nuclear Abs, anti- topoisomerase Abs, and anti-centromere Abs (IgGs)
How do you treat Schleroderma ?
No real standard treatment but giving drugs that will increase blood flow to the extremities will help
What causes type 2 rheumatic fever ?
It is caused by antibodies that are produced during response to bacterial infection ( Group A streptococcus pyrogenes)
What is molecular mimicry ?
When bacterial specific antibodies cross react with heart tissue this is known as molecular mimicry
What is an example of molecular mimicry ?
Streptoccal cell - wall components are very similiar to determinants expressed in heart tissue. Bacteria specific antibodies can bind thesee similiar determinants and cause inflammation —> this can cause heart valve scarring and myocarditis
What is Type 2 Pemphigus Vulgaris ?
Autoimmune condition by IgG specific for 2 proteins resulting in loss of cohesion in heratinocytes in the epidermis
Pemphigus vulgaris is mediated by which antibody ?
IgG
What are the symptoms of Phemphigus ?
Painful chronic blistering of the skin
How do you diagnose Phemphigus ?
Punch Biopsy of the lesion followed by immunofluorescent staining IIgG4 Ab considered pathogenic
How do you treat Pemphigus?
Corticosteroids and other anti-inflammatory mediators
What causes Graves disease ?
Antibody that bind to the thyroid stimulating hormone (TSH) receptor
What is an antagonist ?
A molecule that binds to receptor preventing its interaction with its specific ligand.
What is an agonist ?
A molecule that binds to a receptor, triggering the receptor as if it is interacting with its specific ligand
Describe what you think would happen if an agonist bound to a TSH receptor ?
An agonist will mimic the binding of TSH to the TSH receptor, thus the overproduction of thyroid hormone will ensue
What causes type 3 systemic lupus Erythematosis ?
It is mediated by autoantibodies specific for many self macromolecules ( DNA, Ribosomes, Histones ect. )
Describe the process of the Coomb’s test
3 Steps
- Blood sample from a patient with immune mediated heamolytic anemia ( In which human antigens are bound to the RBC surface)
- The patients washed RBC’s are incubated with antihuman antibodies ( Coomb’s reagent)
- RBC’s agglutinate: The antihuman Ab’s bind to the human Ab’s that are bound to RBC’s and the whole complex precipitates
What is coomb’s reagent and what does it bind to ?
Coomb’s reagent is an Anti-Human antibody that binds to the endogenous antibody specific for the RBC surface molecules
What causes Type 2 Graves disease ?
Greves disease is caused by antibodies that bind to the Thyroid Stimulating Hormone (TSH) receptor mimicing the binding of Thyroid hormone to the receptor —> Overproduction of TSH
What is acute Rheumatic fever?
It is a disease caused when antibodies which are produced in response to bacterial infection cross react with self antigens of the human heart and become autoantibodies.
What is the specific mechanism of acute rheumatic fever ?
Molecular Mimicry- The streptococcal cell wall constituents are very similar to some of the constituents of healthy human heart tissue. Due to this similiarity antibodies produced by the body to fight the infection bind to the healthy tissue and cause an inflammatory reaction that damages the heart tissue
What class of autoimmune disease is acute rheumatic fever ?
Type 2 autoimmune disease- Which is caused by antibodies specific for components of cell surfaces or the extracellular matrix
What are the symptoms of Acute Rheumatic Fever ? (Think we have autoantibodies binding to the heart tissue causing inflammation)
Chest Pain, Fever, Weakness, fatigue, joint pain
Hyperthyroidism, Heat intolerance, nervousness, irritability, warm moist skin, weight loss, enlargement of the thyroid, bulging eyes, and a characteristic stare
Graves disease - Ab’s that bind to thyroid stimulatory hormone receptor and actually mimic binding of the TSH receptor
How do you treat Graves Disease
You will have to remove the thymus or reduce its function