Exam 2- Immunologic Tolerance and Autoimmunity Flashcards
what is central T cell tolerance?
T cells that do not recognize self antigens or recognize self antigens with high affinity are deleted
what prevents T cells from reacting with peripheral self-antigens?
peripheral T cell tolerance
what leads to anergy of a T cell?
T cell recognizes antigens without adequate levels of costimulation
what are the two mechanisms for deletion of T cells?
antigen recognition without costimulation
activation-induced cell death: Fas and Fas ligand
what are CTLA-4 and PD-1?
inhibitory receptors
true/false: binding of CTLA-4 on activated autoimmune T cells with B7 on APCs always leads to deletion of the T cells
false: inactivation
true/false: if a cells expressing Fas binds with a cell expressing FalL, the cell expressing Fas dies by apoptosis
true
what cytokines do T regulatory cells produce?
immunosuppressive cytokines TGF-beta and IL-10
are T regulatory cells CD4+ or CD8+?
CD4+
what is central B cell tolerance?
B cells that recognize self antigens with high affinity are deleted or they change their receptor specificity
what does indolamine 2,3-dioxygnease (IDO) play a role in?
tolerance of an allogeneic fetus
inhibits alloreactive T cell proliferation through catabolizing tryptophan
what is bystander activation?
infection of tissue may induce local innate immune response to the infection: more costimulators (B7) and cytokines by the tissue APCs
what is molecular mimicry?
when a microorganism shares an epitope with a self antigen
polyclonal lymphocyte activators: what does exposure to B cell mitogens such as bacterial lipopolysaccharide lead to?
activation large number of B cells
what are immunologically privileged sites?
central nervous system, eyes, testes
what genes are most commonly associated with autoimmunity?
MHC genes
does Th17 play a larger role than Th1 in autoimmunity ever?
yes, not always
true/false: infection by a virus which expresses one or more antigens that share antigenic identity with the self-antigens can lead to an autoimmune disease
true
true/false: both hypothyroidism and hyperthyroidism are examples of autoimmune diseases
true, but hyperthyroidism more rare to be autoimmune
true/false: serum antibodies against thyroid peroxidase enzyme can be detected in hyperthyroidism cases
true
true/false: Th1 cells are always the most important adaptive immunity cell type in inducing inflammatory autoimmune disorders
false
what antibodies are involved in epidemolysis bullosa acquisita?
IgA and IgG autoantibodies against anchoring fibrils of lower basement membrane: type VII collagen
how are autoimmune diseases treated?
drugs, plasmapheresis, monoclonal antibody treatment
what are the mechanisms of peripheral T cell tolerance?
anergy, deletion, or suppression of autoreactive T cells
what are the costimulating agents for T cells?
B7 and CD28
repeated activation leads to expression of ____________________________ on the surface of T cells
Fas (CD95) and Fas ligand (FasL)
why is Fas called a death receptor?
the cell which expresses Fas and has a FasL bind to it will undergo apoptosis
true/false: persistent high antigenic load in chronic viral infections or cancers lead to T cells upregulating inhibitory receptors
true
do natural Treg cells survive negative selection in the thymus? are they autoreactive?
yes
yes
what cytokines do Treg cells produce after they become activated and differentiate?
immunosuppressive cytokines TGF-beta and IL-10
what do the cytokines that Treg cells produce suppress?
lymphocyte and antigen presenting cell activity
what is the mechanism of human leukocyte antigen-G (HLA-G)?
binds to inhibitory receptors on NK cells to prevent killing of target cells in fetus: do not express MHC molecules
what does complement receptor 1-related protein y (Crry) do?
protects placental tissues from complement-mediated damage (classical pathway)
what antigens does Trypanosoma cruzi share with mammals?
mammalian neurons and cardiac muscle
what leads to systemic lupus erythematosus?
deficiency of C3, a non-MHC molecule
what is the most common cause of blindness in horses?
equine recurrent uveitis
what breed of dog has epidermolysis bullosa acquisita been identified in?
great dane
