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33 Cards in this Set
- Front
- Back
What is the immune response?
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Recognition of a pathogen and a response to eliminate it.
two types of responses: innate and adaptive |
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Adaptive immune response
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specific:each cell only recognises specific antigen(s)
Memory: recognise those previously encountered Self from non self recognition |
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What is an antigen?
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any molecuele which can be specificly recognised by B ot T cells
most are proteins pathogenic orgnsisms may have several antigens |
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immune response
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occurs when an antigen is recognised by a lymphocyte that is capable of responding
lymphocytes are concentrated at lymph, blood, fluids from lungs/GI |
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What makes up the adaptive immune response?
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lymphocytes
B cells: Humoral immunity: produce antibodies T cells: cell mediated, direct contact w antigen or via cytokines |
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3 types of antigen receptor molecules
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Immunoglobulins
T cell antigen receptors Major Histocompatability complexes -enable self recognition |
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name three effects on pathogens as a result of immune system
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Neutralization-binding to antibody
Phagocytosis-englufed Cytotoxicity-killing |
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3 characteristics of t cell antigen receptor
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Located on surface of T cell
Specific to particular antigen TCR never secreted |
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Self recognition
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Regulated by presence of Major Histocompatability complex
or human leucocyte antigen |
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what is MHC restriction?
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When T cells recognise cell bound antigen in association with MHC molecules
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MHC class and t cell response
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the class of MHC will determine which T cell will respond.
Antigen presenting cells express class 2 so present to T helpers Infected body cells express class 1 and present to T cytotoxic cells |
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To ensure self recognition works?
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Adaptive immune response usually require both B and T cell recognition. B cells can interact directly with antigen but need signal from T helpers
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Hypersensitivities
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Type 1: IgE mediated (allergy)
Type 2:Tissue specific Type 3: Immune complex Type 4: Cell- mediated |
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Type 1 Immediate (Allergy)
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Mediated by IgE and mast cells
Mast cells: found in most tissues, particualy connective, serve as stroage for histamine and other inflam mediators |
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how does the allergic response occur?
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IgE molecules bind to the surface of mast cells, resulting in them releasing histamine etc
(by products of complement activation also cause this) |
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Type 2 hypersensitivity -tissue specific
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Damage or destruction of target cell through action of antibody against antigen on cell surface
IgG or IgM antibodies involved |
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Differences between type 2 and type 3
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Both mediated by IgG and IgM antibodies. but in type 3, antibodies are directed against widely distributed or suluble antigens. type 2 is cell surface antigens
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3 types of type 2 reactions to RBC abd platelets.
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Incompatible blood transfusion-recipient sensitive to anitgens on surface of donor cells
Haemolytic disease of newborn Autoimmune haemolytic anaemias-sensitive to self erythrocytes |
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Give and example of a drug induced hypersensitivity
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Quinine, coats cells.
the drug plus cell surface proteins is antigenic. Antibodies and complement cause death and lysis |
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Name three other drug induced hypersensitivities
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Platelets: thromboctyopenic purpura
Granulocytes:granulocytopenia Erythrocytes: haemolytic anaemia |
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Name three type 2 reactions against tissue antigens
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Goodpastures syndrome: glomerular and lung basement membrane
Insulin dept diabetes: insulin cells, or insulin recepts Myasthenia gravis: Ach receptors |
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Type 3 Hypersensitivity
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most type 3 hypersensitivity rxns caused by formation of antibody/antigen (immmune) complexes.these form in blood, but then may be deposited on bv lining.
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Describe the mechanism of type 3 hypersensitivity reactions
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the immune complexes trigger inflamm process.
-complement system -cytokines -basophils and platelets |
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Factors effecting sit of complex deposition
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Vascular permeability
Blood pressure/ turbulence Antigen affinity for specific tissue Size of comlex Class of Ig in complex |
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What is Autoimmunity
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Type 2 or 3 hypersensitivity mechs involved.
Breakdown of self tolerance Genetic predisposition |
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Three ways this could occur?
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Autoimmunity produces disease lesion
Tissue damage as reslut of disease leading to autoantibody prodn Something causes both the lesions and autoantibodies |
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Give 4 examples of pathogenic antibodies
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Thyroid autoimmune disease:antibodies mimic TSH
Diabetes:Antibodies to insulin receptors(rare) Male infertility:Antisperm antibodies |
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Exampls of pathogenic antibodies cont
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Pernicoius amaemia: autoantibody prevents uptake of Vit B12 from gut
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Self tolerance failure
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Molecular mimicry by cross-reactive microbial antigens stim autoreactive B and T cellls
Foreign antigen directly stim B cell without T cell help Cytokine disregulation Inapprop MHC class expression |
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What is Primary(congenital)
immunodeficiency |
Infants who are born without one or more components of the immune system
-developmental defects in the production of the cless or proteins in immune system. |
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What is secondary(aquired)
immunodeficiency? |
as a result of diseases such as diabetes, influenza, measals, cancer.
from viruses(HIV) following transplant/result of chemotherapy |
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HIV immune damage
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death of infected T4 cells
Category A: asymptomatic Category B: symptomatic |
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Stages of HIV infection-indicator conditions
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Candida infn of airways
CMV eye infection Tuberuculosis Pneumonia |