Autoimmunity and Allergies (QUIZ 5) Flashcards
What is autoimmunity
-Immune response to self-antigens leading to damage (congenital- mutations and acquired)
-Autoantigens, autoantibodies, autoreactive (T cells recognizing self)
-Prevented by self-tolerance (think B/T cells selection and central and peripheral)
-Autoimmunity is a failure of tolerance
What is the autoimmune regulator
AIRE, it up-regulates transcription of many genes in thymus
Deletion of AIRE leads to an autoimmunity targeting what
-mainly gladular tissues
-loss of AIRE leads to destruction of endocrine tissues (b/c these make a lot of specialized proteins no found anywhere else)
What disease does AIRE deficiency can lead to
Type I diabetes
What are the four sources of autoimmune
-Ignorant (aren’t active for some reason)
-Low-affinity (need a co-stimulatory signal)
-Anergic cells are non-responsive to antigen
-Other infections can activate them
What is an example of an infection activating autoimmune
-systemic lupus erythematosus
-Some B-cells can bind DNA (dsDNA)
-Damage to tissues releases high amounts of DNA (can overwhelm phagocytosis and can also activate B cells)
-Also can activate TLR (co-stimulatory signal)
A release of what components can activate an autoimmune response
-release of internal component (such as after a heart attack)
-internal components not always displayed (BCR only finds exposed epitopes)
-massice cell death can release them and then activate them
How is somatic hypermutation another source of an autoimmune response
-Somatic hypermutation can lead to generation of self-reactive Ab’s
-A B cell generated against an antigen
-then it mutates for higher affinity (accidently gains self-recognition)
-appears to be a way to kill these cells (apoptosis)
What two responses are required for autoimmune diseases
Requires both B and T cell responses
What is special about Grave’s Disease
-Shows that autoimmunity can cross the placenta
-Attacks the thyroid
-removes Ab’s through plasmapheresis
How is autoimmunity conditions temporary
-many end when the damage is gone
-there could be a cycle (damaged tissues activate autoimmunity and then autoimmune cells damage tissues)
What is epitope spreading
-development of autoimmune responses to epitopes beyond the initiating epitope (ex: BCR that uptakes DNA also takes up histone proteins, present them to T cells, and now responds to histone epitopes)`
What are Cryptic epitopes
-epitopes normally ‘hidden’ from the immune system now being expressed
What are the consequences of epitope spreading
-actually hard to answer
-used for diagnostic testing (presence of certain antibodies=different autoimmune diseases
What are the two methods of a few autoimmune diseases
-antibody (receptor binding and immune complexes)
-Cell-mediated (cytotoxic T cells)
What is Autoimmune hemolytic anemia
-the lysing of red blood cells
-the immune system attacks RBC’s
-antibodies bind antigen on RBC
-leads to complement activation (MAC formation)
-FcR’s and CR’s lead to RBC phagocytosis
What is an antagonist antibody
-blocks signaling of pathways
-antibodies can bind receptors and block receptor function
What is an agonist antibody
-activates receptors (opposite of antagonist)
-antibodies can bidn receptors and ACTIVATE receptor function
What are many autoimmune pathologies caused by
-chronic inflammation
-Goodpasture’s syndrome (Ab against a type of collagen)
-binds to the basement membrane
0Recruits and activates immune system (attacks membranes and kidneys and lings specifically susceptible)
What happens to immune complexes with autoimmune
-usually immune complexes are phagocytized, but with autoimmune, they are constantly being made
What happens with complex formation
-degradation, they can cause damage
-example: mixed essential cryogloulinemia
What is a common sign of autoimmune
-Rheumatoid factor (Ab against Ab)
-Ig that binds Fc of IgG, marker in many autoimmune diseases, ‘anti-antibodies’
How do immune complexes cause damage
-they get stuck (in small vessels and joints)
-Vasculitis
-can induce inflammation
What is an example of cytotoxic T cells in autoimmune
-type 1 diabetes
