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Questions and Answers
What is a common effect of both C5a and C3a?
Which cells in particular does C5a act as a chemotactic agent for?
What is a consequence of inadequate complement proteins (C2, C3, C4, C5, MBL, MAC complex)?
Which condition is associated with deficiencies in C1q?
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What role does C1q play in relation to macrophages and apoptotic bodies?
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What is the proposed role of self-antigens in the development of autoimmunity?
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What makes the alternative pathway the first responder in complement activation?
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What process likely licenses NK cells to ensure their NKIRs are functional?
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In what circumstance do NK cells not kill a cell?
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What happens when NKARs 'over-rule' the NKIRs?
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How do NKARs kill the cell when activated?
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What is the function of perforin in the mechanism of NKAR killing?
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Natural killer cells predominantly kill...
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Which cells protect the body from indiscriminate NK-killing and tissue damage?
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What are the main ligands for RLRs that activate NF-KB?
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What happens when a DAMP activates NLRP3?
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What is the effect of IL-1 release from macrophages?
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What is the function of an inflammasome?
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What is the cellular effect when a cell undergoes pyroptosis?
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What is the function of NLRP3 when it detects diverse signals such as DAMPs and PAMPs?
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Continual presence of self-antigens (ie. nuclear material) in extracellular space can increase the risk of developing _______
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Which of the following cells are important PAMP and DAMP detectors?
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Epithelial and endothelial cells can detect PAMPs and DAMPs
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What is the major cellular source of IL-1?
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Which cytokine has redundant and pleiotropic effects?
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What is the mechanism of fever generation?
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Which cell type is NOT an important cellular source of IL-1?
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What is one of the local functions of IL-1?
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What is the major cellular source of TNF-alpha?
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What is the general role for CRP in acute inflammation?
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Ferritin, Hepcidin, MBL and SAA are all examples of....
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Which of the following effectors change the hypothalamic set point for body temperature?
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What is the main role of Group 1 interferons (IFN-alpha and IFN-beta) in the antiviral response?
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Which cells secrete Group 1 interferons (IFN alpha and IFN beta) in the antiviral response?
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How do type I interferons act to provide protection to viral infection?
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Study Notes
Complement System and Chemotaxis
- C5a and C3a are both potent anaphylatoxins, resulting in increased vascular permeability and recruitment of inflammatory cells.
- C5a acts as a chemotactic agent specifically for neutrophils, eosinophils, and monocytes.
Consequences of Inadequate Complement Proteins
- Deficiencies in complement proteins (C2, C3, C4, C5, MBL, MAC complex) can lead to increased susceptibility to infections and autoimmune diseases.
C1q and Associated Conditions
- Deficiencies in C1q are associated with systemic lupus erythematosus (SLE).
- C1q plays a crucial role in promoting the phagocytosis of apoptotic cells by macrophages.
Self-Antigens and Autoimmunity
- Continual presence of self-antigens, such as nuclear material, in the extracellular space can increase the risk of developing autoimmunity.
Alternative Pathway of Complement Activation
- The alternative pathway is the first responder in complement activation due to its ability to initiate activation on pathogen surfaces without the need for antibodies.
NK Cell Functionality
- Licensing of natural killer (NK) cells occurs through interactions with the major histocompatibility complex (MHC), ensuring their NK inhibitory receptors (NKIRs) are functional.
- NK cells typically do not kill a cell if it expresses sufficient MHC class I molecules.
NK Cell Activation and Mechanism of Killing
- When NK activating receptors (NKARs) over-rule the NKIRs, NK cells are triggered to kill the target cell.
- NKARs induce cell death through the release of cytotoxic granules, which include perforin.
Perforin Functionality
- Perforin functions by creating pores in the target cell membrane, facilitating the entry of granzymes that induce apoptosis.
Natural Killer Cell Targets
- Natural killer cells predominantly kill virus-infected cells, tumor cells, and stressed cells.
Protection Against NK Cell Activity
- Healthy cells express self-MHC and other protective signals to defend against indiscriminate NK killing and tissue damage.
Pathogen Detection
- Main ligands for retinoic acid-inducible gene I-like receptors (RLRs) that activate NF-kB include viral RNA.
- When damage-associated molecular patterns (DAMPs) activate NLRP3, it triggers an inflammatory response through the formation of an inflammasome.
IL-1 and Its Effects
- Release of interleukin-1 (IL-1) from macrophages promotes inflammation, fever, and recruitment of additional immune cells.
- The inflammasome facilitates the maturation and secretion of IL-1.
Cellular Outcome of Pyroptosis
- Pyroptosis results in inflammatory cell death and the release of pro-inflammatory cytokines, differentiating it from apoptosis.
NLRP3 Functionality
- NLRP3 acts as a pattern recognition receptor (PRR) detecting both DAMPs and pathogen-associated molecular patterns (PAMPs) to mount an immune response.
IL-1 Sources and Effects
- Major source of IL-1 is primarily macrophages; it possesses redundant and pleiotropic effects, influencing various immune responses.
- Fever generation involves the hypothalamus's set point alteration due to cytokines such as IL-1 and TNF-alpha.
Other Cytokine Sources
- Major cellular source of tumor necrosis factor-alpha (TNF-alpha) is activated macrophages.
- C-reactive protein (CRP) serves as a marker of acute inflammation.
Acute Phase Proteins
- Ferritin, hepcidin, mannose-binding lectin (MBL), and serum amyloid A (SAA) are examples of acute-phase proteins produced in response to inflammation.
Interferon Response
- Group 1 interferons (IFN-alpha and IFN-beta) are primarily secreted by virus-infected cells and play a critical role in antiviral defense by enhancing the immune response against viral infection.
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Explore frequently asked questions about complement deficiency, including its impact on vasodilation, increased vascular permeability, smooth muscle contraction, and histamine release. Learn about the rarity of complement deficiency and its link to vulnerability to bacterial infections.