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PRC - Lecture 8
Karten in diesem Stapel (54)
- 1Give 2 types of mammalian phagocytic cells.Macrophages
Neutrophils (polymorphonuclear cells) - 2Define phagocytosis.The process of internalization of large particles by the phagocytic cells (macrophages, neutrophils).
- 3What is the activated function of a macrophage? (3)Phagocytosis
Activation of bactericidal mechanisms.
Antigen presentation - 4In what 2 distinct fashions can innate immune cells be activated?- Activation of pattern recognition receptors (PRRs) as part of their innate function.
- Activation of receptors for antibodies that are produced as part of the adaptive immune response. - 5Define PRRs.Pattern Recognition Receptors present on innate immune cells which recognise Pathogen-Associated Molecular Patterns/ PAMPs) on pathogen cell surface.
- 6Give 4 common Pattern Recognition Receptors/ PRRs present on the surface of innate immune cells. Briefly describe them.- Mannose receptor = A c-type lectin. It recognises sugars such as mannose on the surface of many bacteria and some viruses.
- Scavenger receptor = Recognises anionic polymers (teichoic acids, fMet, CpG) and also some unknown PAMPs on many pathogenic cells.
- Toll-like receptor = Situated within the membranes of macrophages and dendritic cells and are extra-cellular sensors of PAMPs.
NOD-like receptor = Cytoplasmic receptors which are intracellular sensors of PAMPs. - 7Name 4 different bacterial PAMPs (Pathogen-associated Molecular Patterns) and the Pattern Recognition Receptors which they recognise.Diacyl lipopetides – TLR-6/ TLR-2
Triacyl lipopeptides – TLR-1/ TLR-2
Flagellin – TLR-5
Lipopolysaccharides – TLR-4 - 8Name 3 different Pattern Recognition Receptors found in the membrane of the endosome of the human cell and name the PAMP (Pathogen-associated Molecular Patterns) microbial components which they recognise within the endosome. compartmentTLR-3 - dsRNA
TLR-7 - ssRNA
TLR-9 - CpGDNA - 9Give examples of 5 different PRRs expressed by macrophages for bacterial components.- Mannose receptor
- LPS receptor (CD14)
- TLR-4
- Fc receptor
- Scavenger receptor - 10When bacteria bind to the PRRs present on the surface of macrophages, what does this initiate for COMMUNICATION function? What does this intiate for EFFECTOR function?Communication: Release of cytokines, chemokines and lipid mediators of inflammation (innate back up).
Effector: Bacterial components are ingested for degradation. - 11What is the specialised function of macrophages?To engulf extracellular pathogens.
- 12Describe the formation of the phagolysosome within the macrophage.- Bacterial component is engulfed by the macrophage to form a phagosome.
- Lysosome within the macrophage fuses with the phagosome to form a phagolysosome (the lysosome has a hostile environment to degrade its contents. - 13Give 6 essential components of both macrophages and neutrophils which aid in killing ingested bacteria.- Acid
- Oxygen free radicals
- Nitric oxide
- Antimicrobial peptides
- Enzymes (lysosomes, acid hydrolases)
- Binding competitors - 14What is the usual pH of a lysosome?ph 5
- 15What condition might a person have if they lack in essential enzymes (lysosomes, acid hydrolases) within their immune cells such as neutrophils and macrophages?Immunodeficiency
- 16What are antibodies?They are soluble proteins that bind to antigens on pathogenic cells.
- 17Where are antibodies made?They are made by B cells and secreted and are part of the adaptive immune system.
- 18In what way do antibodies connect the adaptive and innate immune responses?Antibodies efficiently activate innate immune cells..
- 19In what way do antibodies bind to innate immune cells?The Fc portion of the antibody binds to the Fc receptor on the innate immune cell and generates and immune response.
- 20List 5 innate immune cells.- Macrophages
- Neutrophils
- Eosinophils
- Mast cells
- NK cells - 21What are the 2 main ways in which innate immune cells can be activated?- By the innate immune system using the PRRs found on/ in the innate immune cells.
- By the adaptive immune system using antibodies which bind to Fc receptors on the innate immune cells. - 22List 5 types of receptor expressed by macrophages.- Mannose receptor
- LPS receptor
- TLR-4
- Fc receptor
- Scavenger receptor - 23What type of cells express Fc receptors?Phagocytic cells
- 24What is the process which antibodies use to 'coat' bacteria/ bacterial toxins?Opsonisation
- 25Describe the process of phagocytosis by macropages.- Bacteria are osponised by antibody.
- Fc portion of antibody binds to Fc receptors on surface of macropages.
- Macropages engulf the bacteria/ bacterial toxin.
- Bacteria is lysed by complement. - 26Macrophages are specialised to engulf extracellular pathogens. What other antibody-coated component do macrophages also engulf?Toxins
- 27What is the main function of neutrophils?Phagocytosis and activation of bactericidal mechanisms.
- 28What is the most abundant polymorphonuclear leucocyte in the blood?Neutrophil.
- 29For what antibody do Neutrophils express Fc receptors for?IgG
- 30What takes place upon the binding of IgG to the Fc receptor on Neutrophils?Phagocytosis of antigens bound by IgG (phagolysosome formation).
- 31What is the main function of eosinophils?Killing of antibody-coated parasites (more challenging, parasites very large!)
- 32For what antibody do Eosinophils express Fc receptors for?IgE
- 33What takes place upon the binding of IgE to the Fc receptor on Eosinophils?Enzymes and toxic proteins released.
- 34What would happen on the approach of a Helminth parasite coated with IgE to an Eosinophil for example?The IgE Fc receptor on the surface of the Eosinophil would bind the Fc porton of the IgE antibody on the parasitic surface and this would stimulate the release of cytotoxic granule proteins.
- 35What is the activated function of a basophil?Unknown
- 36What is the activated function of a mast cell?Granules containing histamine and other active agents are released.
- 37For what antibody do Mast cells express Fc receptors for?IgE
- 38What takes place upon the binding of IgE to the Fc receptor on Mast cells?The antigen is bound to antigen-binding site on IgE and this triggers the release of inflammatory mediators (histamine, serotonin, and cytokines) into the tissue.
This triggers inflammation which recruits cells and proteins to sites of infection. - 39What is the activated function of a Natural Killer cell?Releasing lytic granules that kill some virus-infected cells.
- 40When viruses infect cells, what is released and thus, what is activated?Virus-infected cells produce interferon-alpha (IFN-alpha).
This CYTOKINE activates NK cells to kill the virus-infected cell through the release of lytic granules. - 41What is so dangerous about HIV infection concerning the immune system?Because HIV infects vital immune cells such as helper T cells, macrophages and dendrites, we would have to kill off our own immune system if we wanted to remove the entire virus – this is too dangerous.
- 42Why does the body have to be extremely careful when killing off viruses?Since viruses spend the majority of their live living within host cells, the immune system has to kill these infected host cells in order to rid itself of the virus – the body has to be extremely careful to limit damage to self.
- 43What is the name of our INNATE anti-viral cells?NK cells
- 44What 2 types of granules do NK cells contain? What is the function of each of these granules?Perforin – perforates the cell membrane.
Granzymes – Stimulates apoptosis - 45What is the function of the inhibitory receptor on the surface of the NK cell?- It recognises MHC class I on the surface of normal host cells and restrains NK cells activation.
- This is because the body does not want to kill off undamaged cells.
It is a form of communication – informing the host cells that it is NOT infected by a virus. - 46What is the function of the activating receptor on the surface of NK cells? How does it know when a host cell is infected by a virus?- When a ‘target cell’, so a cell that is infected by a virus has an altered conformation of its MHC class I surface component (virus present) or has no MHC class I surface component (tumour formed,)...
- The inhibitory receptor on NK cells cannot recognise the MHC class I in host cells.
- Infact, the NK cell recognises the ‘stress-induced’ receptors on the surface of the effector cell.
- This tells the NK cell that the cell is infected by a virus and that it can go ahead and destroy the cell. - 47What is meant by Antibody-dependent cellular cytotoxicity?- This is a mechanism whereby antigens on the surface of virus-infected cells/ target cells bind IgE antibodies.
- NK cells recognise the Fc portion of the IgE antibody and bind to them via their Fc receptors i.e. they recognise cell-bound antibodies (indicating infection).
- This induces degranulation of NK cellular components (perforins and granzymes) which in turn causes the death of the target cell. - 48What is the main cell type to mediate T-cell activation?Dendritic cell
- 49What are the 2 primary functions of dendritic cells?Antigen uptake in peripheral sites.
Antigen presentation in lymph nodes. - 50What are the 2 main ways in which the innate and adaptive immune responses work together i.e. prime eachother.The innate primes the adaptive immune response by sending dendritic cells to activate T-cells.
The adaptive immune response enhances the effector function of innate immune cells. - 51How are dendritic cells activated?By pattern recognition receptors on their surface binding to PAMPs on pathogens at the site of infection.
- 52Where do dendrites travel when they are activated?They travel to the lymph nodes where they activate naïve T cells.
- 53How would you describe the morphology of lymphocytes? What are the 2 major types?Small, round cells. T lymphocytes and B lymphocytes.
- 54What is it that B cells and T cells recognise?B cells recognise proteins (and small molecules and carbohydrates) and T cells recognise peptides.
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- Beschreibung
- The Immune System 2 - Cells of the immune system.
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- Afronewtzz
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