S1W15 Immunity (FS)
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- Created by: Tino Muronda
- Created on: 24-03-21 15:38
What is the immune system?
The bodys ability to recognise and defend itself against distinct invaders and their products
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What are the two types of immune responses?
Innate and adaptive
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What is the innate imune response?
present from birth, relatively non-specific, no memory
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What is adaptive immunity?
Involves very specific recognition of precipitating agent (antigen), powerful memory generated
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What is the role of neutrophils?
Phagocytose microorganisms later on in immune response
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*** do phagocytes recognise pathogens?
By cell surface receptors that identify agents as 'foreign'
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What are some direct ways of recognition?
Pattern recognition receptors (PRR) bind to molecules - Pathogen associated molecular patterns (PAMPS) only found on microbes, or modified host cells
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What are some indirect ways of recognition?
Serum proteins (Ab, complement, lectins) can coat or 'opsonise' particles which are then recognised by Rs on phagocytes
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What is inflammation?
One of the bodys early defence reactions to infection or damage
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What are the 5 signs of inflammation?
Rubor (redness), Calor (heat), dolor (pain), tumor (swelling) and loss function
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What is the process of activating immune cells during inflammation?
Mediators are released from activated tissue
Stimulate release of granulocytes and monocytes from bone marrow
Increase expression of adhesion molecules
Stimulate release of granulocytes and monocytes from bone marrow
Increase expression of adhesion molecules
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What are some example of inflammatory mediators?
Cytokines/chemokines
Enzymatic cascades
Complement components
Prostaglandins and leukotrienes
Enzymatic cascades
Complement components
Prostaglandins and leukotrienes
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What is the role of IL-1, IL-6 and TNFa?
Cytokines
Early alarm signals causing local and sytemic activation of fever, vascular permeability, production of acute phase proteins and increased adhesion molecule expression
Early alarm signals causing local and sytemic activation of fever, vascular permeability, production of acute phase proteins and increased adhesion molecule expression
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What is the role of IL-12?
Cytokine
Activates adaptive immune responses (T cells)
Activates adaptive immune responses (T cells)
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What is ther role of inteferon y (IFNy)?
Cytokine
Contributes to chronic inflammation by recruiting to sites of damage/infection
Contributes to chronic inflammation by recruiting to sites of damage/infection
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What are some anti-inflammatory cytokine examples?
IL-10 and transforming growth factor-b
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What are chemokines?
Defined by the presence of 4 cysteine residues & sequence of amino acids involving the first two of these
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What are natural killer cells?
T cells
Can attack tumor cells by antibody dependent cellualr cytotoxicity (ADCC)
Can attack tumor cells by antibody dependent cellualr cytotoxicity (ADCC)
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What is the killing mechanisms of Natural killer cells?
Form pores in target cell membrane by secreted molecules
Induce apoptosis
Induce apoptosis
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What is an antigen(Ag)?
Any substance that binds to specific receptors on lymphocytes
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What is the antigenic determinant or epitope?
The part of the Ag that binds to the receptors
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What are immunogens?
Any molecule or group of molecules that induce an immune response
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What is a hapten?
Small molecule that can act as an epitope but not elicit an immune response
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What is the antibody structure?
Monomer: A flexble Y-shaped molecule with four protein chains - 2 light and 2 heavy chains
Variable regions: Contain the antigen binding sites, vary on each antiboy
Constant region: Stem of monom and lower parts of Y arms
Fc region: Stem of monomer only
Variable regions: Contain the antigen binding sites, vary on each antiboy
Constant region: Stem of monom and lower parts of Y arms
Fc region: Stem of monomer only
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What are the 5 classes of antibodies?
IgG, IgM, IgA, IgE and IgD
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What is the function of IgA?
Agglutination and neutralisation
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What is the function of IgE?
Triggers release of histamines from basophils and mast cells
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What is the function of IgG?
Complement activation, agglutination, opsonization and neutralisation, crosses placenta to protect fetus
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What is the functiong of IgM?
Complement activation, aglutination and neutralisation
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What is cell-mediated immunity?
Host defences that are mediated by antigen-specific T cells and various non-specific cells of the immune response
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What are naive T cells?
T cells that have not yet been stimulated by antigen since leaving the thymus
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What are T memory cells?
T cells that have an antigen presented o them and return to resting state. They are long lived and can be reactivated
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What are T effector cells?
T cells that have specialised functions e.g. secretion of cytokines (helper), lysis of target cells (cytotoxic) or regulatory
Derived from naive or memory cells, short lived in an active state, but require further stimulation for full function
Derived from naive or memory cells, short lived in an active state, but require further stimulation for full function
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What is Ag class 1 processing?
All nucleated cells and proteases
Endogenous antigens
Broken down in proteasomes and loaded into MHC I in ER
Endogenous antigens
Broken down in proteasomes and loaded into MHC I in ER
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What is Ag class 2 processing?
APC
Exogenous antigens
Broken down in endosomes or phagosomes and loaded into MHCII in endosomes
Exogenous antigens
Broken down in endosomes or phagosomes and loaded into MHCII in endosomes
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What are the three signals to activate T cells?
Signal 1: TCR/MHC with antigen, stabilised by adhesion molecules
Signal 2: Co-stimulatory molecules(B7 on the APC which binds to CD28 on the T cell)
Signal 3: directs T cell differentiation into different subsets - these are cytokines made by the same APC
Signal 2: Co-stimulatory molecules(B7 on the APC which binds to CD28 on the T cell)
Signal 3: directs T cell differentiation into different subsets - these are cytokines made by the same APC
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What are the main types of effector T cells?
CD4+: produce cytokines to help B cells,other T cells and other cells to perform their functions
CD8+: usually cytotoxic in nature (require activation and cytokines from activated CD4+ cells
CD8+: usually cytotoxic in nature (require activation and cytokines from activated CD4+ cells
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What is the function of MHC molecules?
Bind peptide fragments derived from pathogens and display them on cell surface to be recognised by T cells
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What is the function of HLA?
Present foreign antigens to activate T cell response
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What is active and passive immunity?
Active immunity is when our own immune system is responsible for protecting us from pathogens.
Passive immunity is when we are protected from a pathogen by immunity gained from someone else.(breast milk or antibody injection)
Passive immunity is when we are protected from a pathogen by immunity gained from someone else.(breast milk or antibody injection)
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Other cards in this set
Card 2
Front
What are the two types of immune responses?
Back
Innate and adaptive
Card 3
Front
What is the innate imune response?
Back
Card 4
Front
What is adaptive immunity?
Back
Card 5
Front
What is the role of neutrophils?
Back
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