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58 Cards in this Set
- Front
- Back
What are the main parts of the innate immune system?
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skin
phagocytes NK cells complement Toll like receptors- (stimulate innate immune response) |
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What cell controls cell mediated adaptive immunity?
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T-lymphocytes
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What cell controls humoral adaptive immunity?
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B cells- produce antibodies
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How do T cells recognize cell bound antigen?
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They used a TCR or T cell receptor
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What makes up the TCR, and what is is complexed with?
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This has a variable (antigen binding region)
the constant region- has CD3 and Xi chain dimer (funny E). Used for signal transduction, NOT binding |
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What is the usefulness of TCR gene rearrangments
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used as a molecular marker of T-lineage cells
used to classify lymphoid malignancies |
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What do CD4 cells bind to?
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Class 2 MHC's
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What do CD4+ cells do?
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these are helper cells, they secrete cytokines that influence other cells
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What do TH1 cells secrete?
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IL-2, IFN- involved in cell mediated immunity
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What do TH2 cells secrete?
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IL-4, and IL-5, used in humoral immunity
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What do CD8+ cells bind to?
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MHC class 1
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What do CD8+ cells do?
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these are cytotoxic cells, kill infected cells directly
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What are the two signals a T cell needs for activation?
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TCR (CD+MHC)
and CD28 + costimulatory molecule on MHC |
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What do B cells become when stimulated by antigen?
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these become plasma cells
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What is the antigen binding component on B cells
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Surface IgM or IgD are used for antigen binding
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What is the usefulness of rearranged IG genes on B cells?
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This is used as a molecular marker for B cells
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What are the two types of dendritic cells, and what do they do?
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Interdigitating dendritic cells (Langerhans cells)- Used for antigen presenting in primary immune responses
Folicular dendritic cells- found in germinal centers of lymphoid follicles- These have Fc receptor for IgG, trap antigen bound to antibody |
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What is the innate ability of NK cells?
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these can lyse tumor and infected cells without prior stimulation
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What are the CD markers of NK cells?
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16 and 56
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What does CD16 do? and what is ADCC?
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this is a Fc receptor for IgG
Allows NK cells to lyse IgG coated target cells--this is called ADCC (antibody dependent cell mediated cytotoxicity) |
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What are the two receptors on NK cell membranes and what do they do?
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theres a inhibitor which binds normal class 1 MHC's
and there is a killing one, turned on by some molecule on target cell |
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What do NK cells secrete?
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cytokines
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What are MHC complexes used for?
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peptide antigen presentation
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What chromosome are MHCs from?
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chromosome 6
called MHC or HLA gene cluster |
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What are the three categories of the HLA system?
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Class 1- coded by A,B,C.- presents on all nucleated cells- displays abnormal peptides
Class 2- coded by D- only found on monocytes, macrophages, dendritic cells, and B cells Class 3- some of the complement components |
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What is the best known disease assocaited with HLA?
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ankylosing spondylitis
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What are the three categories of HLA associated diseases?
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Inflammatory diseases (ankylosing spondylitis)
Inherited erros of metabolism Autoimmune diseases |
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What is a type I hypersensitivity?
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immediate anaphylactic rxn due to IgE
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What is a type II hypersensitivity?
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Antibody mediated (usually cross reaction)
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What is a type III hypersensitivity?
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immune complex mediated- body produces antibodies and complement that deposit into joints and tissues, causing inflammation
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What is a type IV hypersensitivity?
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cell mediated hypersensitivity
activate T cells |
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What T cells are activated in a type 1 hypersensitivity?
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Th2 cells- secretes IL-4 - this causes IgE secretion from B cells
and IL-5- activates eosinophils |
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What is the chain of events in a type 1 hypersensitivity rxn?
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Mast cells are sensitized by IgE antibody
The mast cells are activated and release mediators upon exposure to antigen (activated by IgE cross linking) |
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What are the immediate responses of a type 1 hypersensitivity rxn?
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Vasodilation
Vascular Leakage Smooth muscle spasm (5-30 min) |
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What is the late phase reaction of a type 1 hypersensitivity rxn?
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2-8 hours later
inflammation, tissue destruction |
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What cell is important in late phase of type 1 hypersensitivity rxns?
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Eosinophils- these contain many mediators that are responsible for many symptoms
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What is Atopy?
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a predisposition to develop hypersensitivity reactions to inhaled agents
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What are the three effector mechanisms of antibody mediated injury in type II hypersensitivity rxns?
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Opsonization and phagocytosis
Inflammation antibody mediated cellular dysfunction |
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What are the four clinical situations in which opsonization and phagocytosis occur? (in type II hypersensitivity rxns)
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Transfusion reactions
erythroblastosis fetalis Autoimmune hemolytic anemia, agranulocytosis, thrombocytopenia some drugs (penicillin) |
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What two diseases are examples of antibody mediated cellular dysfunction?
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Myasethnia gravis- with antibodies inhibiting the NMJ
Graves disease- with antibodies stimulating the thyroid |
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What type types of antigens can cause immune complex injury in type III hypersensitivity rxns?
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Exogenous (foreign protein, bacteria, viruses)
Endogenous- self antibodies against self |
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What are the two patterns of injury seen in type III hypersensitivity rxns?
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Circulating immune complexes (antigen combines with antibody in circulation, deposed in vessel walls)- called Generalized*
In situ immune complexes (complexes form at extravascular sites, where antigen may have been deposited before)- Localized** |
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What are the three phases of the systemic form of type III hypersensitivity rxns?
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Immune complex formation
immune complex deposition (small ones circulate longer, large one removed by MPS system- can be overwhelmed) inflammation rxn @ sites of deposition- about 10 days after antigen administration |
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What is the major morphologic feature of immune complex injury?
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tissue injury usually occurs in kidneys, joints, and small vessels.
Acute necrotizing vasculitis (fibrinoid necrosis in vessel walls) 10 days after administration of the antigen, causes fever, arthalgias, urticaria, lymph node enlargement, complement, neutrophil and macrophage activation |
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What are the two types of reactions of type IV hypersensitivity rxns? and what cells causes each?
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Delayed type hypersensitivity rxns, with CD4 cells
and Direct cell cytotoxicity with CD8 cells |
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What is the classic example of delayed type IV hypersensitivity?
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Mantoux reactions (the TB test). CD4 cells cause this
which is elicited in people already sensitized to tubercle bacillus by previous infection |
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How does a delayed type hypersensitivity rxn occur?
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Niave CD4 cells recognize an antigen in a class II MHC.
-this produces effector and memory CD4 cells of TH1 type. APC's produce IL-12 which turns on Th1 type T cells. NK cells and Th1 produce INFy- which activates macrophages turns into a feedback loop |
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What are the two hypersensitivity types in transplant rejection
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cell mediated and antibody mediated
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How are grafts directly rejected?
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T cells recognize graft MHC complexes.
CD4 helper cells triggered by class II MHC's on grafts CD8's recognize class I MHC's and kill them |
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How are grafts indirectly rejected?
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CD4+ cells recognize donor MHC molecules after APC's bring them in.
this causes antibody production |
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What is hyperactue rejection?
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the body already has preformed antibodies to the donors tissues - causes ischemic death of graft
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what is acute graft rejection?
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days to weeks (but can be held off for months)
by either cellular or humoral methods humoral causes rejection vasculitis |
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What are the signs of chronic graft rejection?
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months to years later,
you see vascular changes, interstitial fibrosis, and loss of parenchyma immunosuppression will not help |
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How do you increase graft survival?
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HLA matching, and immunosuppression therapy
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What are the three complications of Allogenic hematopoietic stem cell transplants?
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transplant rejection
graft verses host disease immune deficiencies |
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What mediates transplant rejection in allogenic hematopoeitc stem cell transplants?
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Mediated by radiation resistant T-cell, and NK cells in the host
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What three organs are target in GVH disease?
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liver, skin, and gut
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How does GVH disease happen?
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you transplant immune competent cells into an immune compromised pt.
the T cells from the donor react to their new surroundings |