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45 Cards in this Set
- Front
- Back
On which type of cell is the CD8 co-receptor predominantly expressed?
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Cytotoxic T cells (also natural killer cells and dendritic cells)
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What is the function of CD8?
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A co-receptor for the T cell receptor
Binds to class I MHC protein |
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What is a healthy/normal CD4:CD8 ratio?
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2:1
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What is the role of CD4+ T cells and how do they carry it out?
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"Helper" T cells, they secrete cytokines that influence virtually all other cells of the immune system.
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What is the role of CD8+ T cells?
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"Cytotoxic" - Important in directly killing virus infected or tumor cells.
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To what to CD4+ helper T cells respond?
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Peptide antigens when presented by class II MHC molecules.
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To what to CD8+ T cells respond?
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Antigens associated with class I MHC
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What is the role of NK cells?
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Able to lyse a variety of tumor cells, virally infected cells and some normal cells without previous sensitization.
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To what part of the immune system to NK cells belong?
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Innate
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Where are NK cells produced?
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In the bone marrow
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What are the main types of receptors expressed by NK cells?
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Fc receptors for IgG
KARS - killer activation receptors KIRS - killer inhibitory receptors |
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What do KIRS on NK cells do?
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Killer inhibitory receptors recognise MHC class I leader peptides presented in an MHC like molecule HLA-E
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How do NK cells detect virus infected cells?
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Reduced MHC class I detected by Killer Inhibitors Receptors allowing activation of killer activation receptors.
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How do NK cells mediate killing?
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Release of granule contents (perforins and granzymes) onto the surface of the infected cell.
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What is perforin?
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A protein released by NK cells and cytotoxic T cells which can create pores in the cell membrane.
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Name three types of denritic cells and their location?
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Langerhans cell - skin
Interdigitating cells - lymph node T cell areas Follicular dendritic cells - B cell follicles of the lymphoid tissues |
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What type of MHC do dendritic cells use?
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Class II
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What is the main function of neutrophils?
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Patrol bloodstream in search of invading microbes
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How is the alternative complement pathway activated?
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Interaction of C3 with certain types of molecules on microbes or by self molecules which react with these molecules.
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What are the four major functions of the complement system?
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Initiation of infammation by direct activation of mast cells.
Attraction of neutrophils Enhancement of attachment of the microbe to the phagocyte Killing of the microbe by the membrane attack complex |
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What is the role of C reactive protein? (Both in general and how)
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Acute-phase protein.
Binds phosphocholine on dead or dying cells and some bacteria in order to activate the complement system. |
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What do toll-like receptors recognise?
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Structurally conserved molecules derived from microbes.
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What is the most abundant immunoglobulin in the blood?
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IgG
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What is the only antibody to cross the placenta?
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IgG
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What is the major immunoglobulin present in external secretions such as colostrum, milk and saliva?
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IgA
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What does humoral immunity mean?
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Antibody-mediated
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What are the components of the membrane attack complex?
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C5b, C6, C7, C8, C9
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What is an opsonin?
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A substance that acts as a binding enhancer for the process of phagocytosis.
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What are the attributes of the peptidoglycan layer of gram positive bacteria?
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Thicker, multilayer
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What are the attributes of the peptidoglycan layer of gram negative bacteria?
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Thinner, single layer
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Do gram positive or gram negative bacteria have teichoic acid in their membranes?
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Gram positive
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Do gram positive or gram negative bacteria have lipopolysaccharide (endotoxin) in their cell walls?
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Gram negative
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What is the approximate diameter of bacteria?
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1-5um
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What is the approximate diameter of a virus?
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0.02-0.2um
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What are the components of the carbohydrate backbone of peptidoglycan?
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N-acetylmuramic acid and N acetylglucosamine
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What is the only bacteria without a cell wall composed of peptidoglycan?
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Mycoplasma
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What is the first stain in Gram staining and what does it do?
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Crystal violet stains all cells blue/purple
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What colour to Gram positive colours stain in the gram stain?
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Blue
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What colour do gram negative bacteria stain in the gram stain?
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Red/Pink
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How would you classify streptoccus?
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Gram positive cocci
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How would you classify staphylococcus?
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Gram positive cocci
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How would you classify neisseria?
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Gram-negative cocci
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How would you classify escherichia?
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Gram negative, facultative, rod
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What do interferons do?
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Inhibit virus replication by blocking the production of viral proteins, primarily by degrading viral mRNA via induction of the synthesis of a ribonuclease which cleaves viral mRBA but not cell mRNA
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What are the most potent inducers of interferons?
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Viruses and double-stranded RNA
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