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Micro lecture 9
| Question | Answer |
|---|---|
| Natural Killer Cells (NK cells) | large lymphocytes with some azurophilic cytoplasmic granules |
| What are the target cells of NK cells? | viruses, intracellular pathogens, tumor cells |
| What do NK cells use? | cytoplamic granules containing perforins and granzyme |
| How does an NK cell determine whether or not to kill a cell? | It recognizes both activating and inhibitory signals on target cell surface; if the inhibitory signal is absent or down-regulated, the NK cell kills the target. |
| ADCC | Antibody Dependent Cell-mediated Cytotoxicity |
| How does ADCC work? | Antibody binds antigens on target cell surface; Fc receptors on NK cells recognize antibody; Cross-linking of Fc receptors signals the NK cell to kill the target cell; Target cell dies. |
| What cells kill by ADCC? | Neutrophils; NK cells; Eosinophil; Macrophages |
| What are the effector functions of NK cells? | Killing stressed or infected cells and secretion of cytokines, especially interferon-γ. |
| What are eosinophil's targets? | Parasitic worms (helminths). |
| The complement system is... | A set of serum proteins designated numerically according to the order of discovery |
| Complement activation can result in: | opsonization or lysis of a foreign cell, attraction of phagocytes, clearance of immune complexes |
| How can complements be activated? | Classical Pathway (adaptive immune system) Alternative Pathway Lectin Pathway |
| Name some "alternative complement" activators | Many gram-negative bacteria, lipopolysaccharides of gram-neg bacteria, many gram-positive bacteria, teichoic acid, fungal and yeast cell walls, some viruses/virus-infected cells, some tumor cells, parasites. |
| Name the "alternative pathway" complement activation sequence. | C3b binds to surface of foreign cell; C3 convertase formation; response amplification; formation of C5 convertase; membrane attack complex. |
| What is MAC | Membrane Attack Complex |
| What is Lectin? | a carbohydrate-binding protein |
| What does MBL stand for? | Mannose binding lectin |
| What does MBL do? | Binds to mannose residues common on surface microbes in bacteria and fungi but not on the surface of vertebrate cells. |
| What does the binding of MBL do? | It attracts additional proteases and initiates complement activation. |
| What is the classical pathway activated by? | An antigen-antibody complex on the surface of the pathogen. |
| What are the major functions of complement? | 1. Lysis of foreign cells. 2. Opsonization. 3. Chemoattraction of phagocytes to infected area/inflammation. |
| Rubar | redness (think ruby) |
| tumor | swelling |
| calor | heat (like in spanish) |
| dolor | pain (like in latin) |
| What are the four enzymatic systems? | kinin system; coagulation system; fibrinolytic system; complement cascade |
| Inflammation can be... | acute or chronic, local or systematic |
| Cytokines | small, secreted proteins |
| Cytokines are produced by mainly... | T-helper cells, dendritic cells, macrophages |
| Name 3 pro-inflammatory cytokines | IL-1 (interleukin-1), IL-6 (interleukin-6), TNFα (tumor necrosis factor α) |
| Name 3 systematic acute phase responses | fever, acute-phase proteins, leukocytes |
| What classifies a fever? | When the body is above 37 degrees C |
| When does a fever occur? | When chemicals called pyrogens (pyro = fire, gen = birth) trigger the hypothalamus to increase body temp. |
| Name some pyrogens | Bacterial toxins, cytoplasmic contents of bacteria, antibody-antigen complexes, Cytokines IL-1, IL-6, and TNFα |
| How does IL-1 cause a fever? | IL-1 causes hypothalamus to secrete prostaglandin which resets "thermostat." Increases muscle contractions and metabolism, constricts blood vessels. |
| Name 3 benefits of fever. | Enhances interferon effects, Inhibits growth of some microorganisms, May enhance phagocyte performance, cells of specific immunity, and tissue repair. |
| The presence of _________ neutrophils is indicative of an ongoing ________ _________. | band-type; bacterial infection. |
| What are acute-phase proteins? | A class of proteins whose plasma concentrations increase (positive) or decrease (negative) in response to inflammation. |
| Name 2 acute-phase reactants the liver produces. | C-reactive protein, mannose-binding protein |
| What does the C-reactive protein do? | Binds to microbial cell, activates complement, C3b opsonizes the cell and increases phagocytosis. |
| What does mannose-binding protein do? | activates complement system |
| What are the Type I Interferons? | IFNα and IFNβ |
| What is the Type II Interferon? | IFNγ |
| What does IFNγ do? | Activates macrophages. |
| Type I IFNs are secreted in response to _____ ______ | Viral PAMPs |
| What are the two types of adaptive immunity? | Humoral and Cellular |
| Plasma | the fluid fraction of the blood |
| Serum | fluid that remains from clotted blood |
| antibodies | protein molecules that bind in a very specific way to antigens |
| antigen | foreign substance that can bind to the antigen receptors of immune cells (B cell receptors or antibodies, and T cell receptors) |
| immunogen | substance capable of provoking an immune response |
| epitope | localized region on the surface of the antigen that is capable of eliciting an immune response and of combining with a specific antigen receptor. |
| hapten | small molecule that reacts with a specific antibody but cannot induce the formation of antibodies unless bound to a carrier molecule. |
| An antibody molecule has 2 ______ chains and 2 ______ chains. | light; heavy |
| Name 2 antibody fragments defined by digestion with proteases. | Papain, Pepsin |
| Fab | Fragment, antigen binding |
| Fc | Fragment, crystallizable |
| F(ab)2 | Fragment, like Fab (dimer) |
| Digestion by papain causes | Fab and Fc |
| Digestion by pepsin causes | F(ab)2 |
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