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Questions and Answers
Which type of immune response is triggered by tissue damage or pathogen invasion?
Which type of immune response is triggered by tissue damage or pathogen invasion?
What does the physiological barrier of skin do to microbes?
What does the physiological barrier of skin do to microbes?
Which enzyme found in tears and saliva cleaves peptidoglycans of bacterial cell walls?
Which enzyme found in tears and saliva cleaves peptidoglycans of bacterial cell walls?
What is the main function of dendritic cells in the innate immune response?
What is the main function of dendritic cells in the innate immune response?
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What is the role of neutrophils in the innate immune response?
What is the role of neutrophils in the innate immune response?
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Which of the following best describes the main focus of Theme 2 - Innate Immunity?
Which of the following best describes the main focus of Theme 2 - Innate Immunity?
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What is the primary function of Toll-like receptors (TLRs) and Pattern Recognition Receptors (PRRs) in innate immunity?
What is the primary function of Toll-like receptors (TLRs) and Pattern Recognition Receptors (PRRs) in innate immunity?
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What is a key role of cytokines and chemokines in inflammation?
What is a key role of cytokines and chemokines in inflammation?
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Which process involves engulfing and digesting pathogens or cellular debris by immune cells?
Which process involves engulfing and digesting pathogens or cellular debris by immune cells?
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What is a significant feature of the complement system activation?
What is a significant feature of the complement system activation?
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Which stage of phagocytosis involves the binding of Pathogen Associated Molecular Patterns (PAMPs) or Damage Associated Molecular Patterns (DAMPs) to Pattern Recognition Receptors (PRRs) on phagocytes?
Which stage of phagocytosis involves the binding of Pathogen Associated Molecular Patterns (PAMPs) or Damage Associated Molecular Patterns (DAMPs) to Pattern Recognition Receptors (PRRs) on phagocytes?
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Which molecule can be recognized by Dectin-1, a Pattern Recognition Receptor expressed on myeloid lineage cells?
Which molecule can be recognized by Dectin-1, a Pattern Recognition Receptor expressed on myeloid lineage cells?
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Scavenger receptor SR-A, found on macrophages (MFs) and some endothelial cells, is known to bind which molecule?
Scavenger receptor SR-A, found on macrophages (MFs) and some endothelial cells, is known to bind which molecule?
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What is the primary function of Mannose Receptor, another Pattern Recognition Receptor expressed on macrophages and dendritic cells?
What is the primary function of Mannose Receptor, another Pattern Recognition Receptor expressed on macrophages and dendritic cells?
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Which stage of phagocytosis involves the actual internalization of the recognized pathogen or particle by the phagocyte?
Which stage of phagocytosis involves the actual internalization of the recognized pathogen or particle by the phagocyte?
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In phagocytosis, when cells bind opsonins coating the surface of particulate matter or microbes, this type of recognition is classified as:
In phagocytosis, when cells bind opsonins coating the surface of particulate matter or microbes, this type of recognition is classified as:
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What is the main function of Psoriasin on skin and secretions?
What is the main function of Psoriasin on skin and secretions?
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Which antimicrobial protein is particularly effective in disrupting bacterial membranes, especially in bacteria?
Which antimicrobial protein is particularly effective in disrupting bacterial membranes, especially in bacteria?
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Who first described the phenomenon of phagocytosis?
Who first described the phenomenon of phagocytosis?
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Which type of cells primarily carry out phagocytosis?
Which type of cells primarily carry out phagocytosis?
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What is the general purpose of endocytosis in a cell?
What is the general purpose of endocytosis in a cell?
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Which mechanism of endocytosis is characterized by the specific uptake of ligands or immune complexes?
Which mechanism of endocytosis is characterized by the specific uptake of ligands or immune complexes?
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What is the main size range of particles that are internalized and digested during phagocytosis?
What is the main size range of particles that are internalized and digested during phagocytosis?
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Which antimicrobial peptides aggregate to form pores in cytoplasmic membranes?
Which antimicrobial peptides aggregate to form pores in cytoplasmic membranes?
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Which surfactant protein functions by blocking bacterial surface components through binding?
Which surfactant protein functions by blocking bacterial surface components through binding?
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What is the role of Cathelicidins in disrupting microbial membranes?
What is the role of Cathelicidins in disrupting microbial membranes?
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Which receptor is responsible for binding LPS from gram-negative bacteria on monocytes?
Which receptor is responsible for binding LPS from gram-negative bacteria on monocytes?
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Who identified TLR4 as the receptor for LPS and received the Nobel Prize for this discovery?
Who identified TLR4 as the receptor for LPS and received the Nobel Prize for this discovery?
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Which intracellular receptors interact with PAMPs and DAMPs, activating the NFkB pathway and autophagy?
Which intracellular receptors interact with PAMPs and DAMPs, activating the NFkB pathway and autophagy?
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Which receptors bind viral dsRNA and initiate anti-viral cytokine production?
Which receptors bind viral dsRNA and initiate anti-viral cytokine production?
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What is the function of opsonins in the immune response?
What is the function of opsonins in the immune response?
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What is the role of leucine-rich repeats in Toll-like receptors?
What is the role of leucine-rich repeats in Toll-like receptors?
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Which signaling pathways are activated upon ligation of cell surface Toll-like receptors?
Which signaling pathways are activated upon ligation of cell surface Toll-like receptors?
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What is the main difference between cell surface and intracellular Toll-like receptors?
What is the main difference between cell surface and intracellular Toll-like receptors?
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Which molecules can be recognized by AIM2-like receptors and cGAS/STING in the context of immune response?
Which molecules can be recognized by AIM2-like receptors and cGAS/STING in the context of immune response?
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Innate immunity is considered the 'specific' arm of the immune system.
Innate immunity is considered the 'specific' arm of the immune system.
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Phagocytosis is a process involved in the adaptive immune response.
Phagocytosis is a process involved in the adaptive immune response.
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Toll-like receptors (TLRs) are involved in innate immune cell activation.
Toll-like receptors (TLRs) are involved in innate immune cell activation.
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The complement system activation only involves one main cell type.
The complement system activation only involves one main cell type.
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Cell-mediated innate immunity primarily involves chemical mediators rather than cells.
Cell-mediated innate immunity primarily involves chemical mediators rather than cells.
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The first line of defense, known as FAST, is triggered by tissue damage from trauma or infection.
The first line of defense, known as FAST, is triggered by tissue damage from trauma or infection.
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Innate immunity comprises three main types of defensive barriers: Anatomical, Physiological/chemical, and Inflammatory.
Innate immunity comprises three main types of defensive barriers: Anatomical, Physiological/chemical, and Inflammatory.
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Skin's acidic environment with a pH range of 3-5 promotes the growth of microbes.
Skin's acidic environment with a pH range of 3-5 promotes the growth of microbes.
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Lysozyme is an enzyme found in tears and saliva that cleaves peptidoglycans of bacterial cell walls, particularly gram-negative bacteria.
Lysozyme is an enzyme found in tears and saliva that cleaves peptidoglycans of bacterial cell walls, particularly gram-negative bacteria.
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Neutrophils are categorized as antigen-presenting cells in the innate immune system.
Neutrophils are categorized as antigen-presenting cells in the innate immune system.
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Natural killer cells are part of the adaptive immune response rather than the innate immune response.
Natural killer cells are part of the adaptive immune response rather than the innate immune response.
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Pattern Recognition Receptors (PRRs) on phagocytes only bind to Pathogen Associated Molecular Patterns (PAMPs) and not to Damage Associated Molecular Patterns (DAMPs).
Pattern Recognition Receptors (PRRs) on phagocytes only bind to Pathogen Associated Molecular Patterns (PAMPs) and not to Damage Associated Molecular Patterns (DAMPs).
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Scavenger receptor SR-A is only found on dendritic cells, not on macrophages.
Scavenger receptor SR-A is only found on dendritic cells, not on macrophages.
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Dectin-1 binds to β1-4 glucan found on fungi and bacteria.
Dectin-1 binds to β1-4 glucan found on fungi and bacteria.
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The Mannose Receptor has 10 extracellular domains.
The Mannose Receptor has 10 extracellular domains.
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Phosphatidylserine is a Damage Associated Molecular Pattern (DAMP) found on the surface of damaged cells and apoptotic cells.
Phosphatidylserine is a Damage Associated Molecular Pattern (DAMP) found on the surface of damaged cells and apoptotic cells.
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Indirect recognition in phagocytosis involves cells binding directly to the pathogen/particle.
Indirect recognition in phagocytosis involves cells binding directly to the pathogen/particle.
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Psoriasin disrupts microbial cell membranes by binding to them.
Psoriasin disrupts microbial cell membranes by binding to them.
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SP-A and SP-D are examples of defensins.
SP-A and SP-D are examples of defensins.
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Cathelicidins are mainly found on skin and secretions.
Cathelicidins are mainly found on skin and secretions.
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Endocytosis is the general purpose of a cell externalizing material that is present on the inside of the cell (intracellular).
Endocytosis is the general purpose of a cell externalizing material that is present on the inside of the cell (intracellular).
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Pinocytosis involves specific uptake of ligands, growth factors, or hormones via receptors.
Pinocytosis involves specific uptake of ligands, growth factors, or hormones via receptors.
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Phagocytosis is carried out by B cells and mast cells to internalize, kill, or digest particulate matter.
Phagocytosis is carried out by B cells and mast cells to internalize, kill, or digest particulate matter.
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Receptor-mediated endocytosis involves invagination of the plasma membrane to form 'clathrin coated pits'.
Receptor-mediated endocytosis involves invagination of the plasma membrane to form 'clathrin coated pits'.
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Macro-pinocytosis is a mechanism where cells take in large 'gulps' of extracellular material.
Macro-pinocytosis is a mechanism where cells take in large 'gulps' of extracellular material.
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Phagocytes are involved in 'cell drinking' through pinocytosis to bring in nutrients.
Phagocytes are involved in 'cell drinking' through pinocytosis to bring in nutrients.
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'Cell surface receptors cluster and associate clathrin around 'pits' in endosomes during pinocytosis.'
'Cell surface receptors cluster and associate clathrin around 'pits' in endosomes during pinocytosis.'
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SR-B can only bind oxidised LDL and vimentin on the surface of apoptotic cells.
SR-B can only bind oxidised LDL and vimentin on the surface of apoptotic cells.
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CD14 has a signaling domain in its cytoplasmic tail.
CD14 has a signaling domain in its cytoplasmic tail.
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Toll gene was identified in Drosophila by Beutler in 1996.
Toll gene was identified in Drosophila by Beutler in 1996.
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TLR5/5 recognizes CPG DNA from gram-positive bacteria and fungi.
TLR5/5 recognizes CPG DNA from gram-positive bacteria and fungi.
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TLR9 detects single-stranded DNA and double-stranded RNA.
TLR9 detects single-stranded DNA and double-stranded RNA.
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B cells, T cells, and granulocytes express all Toll-like receptors.
B cells, T cells, and granulocytes express all Toll-like receptors.
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NOD-like receptors interact with extracellular PAMPs and DAMPs.
NOD-like receptors interact with extracellular PAMPs and DAMPs.
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RIG-like receptors bind DNA molecules from bacteria and viruses.
RIG-like receptors bind DNA molecules from bacteria and viruses.
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Opsonins like IgG enhance cell attachment by cleaving pathogen cell walls.
Opsonins like IgG enhance cell attachment by cleaving pathogen cell walls.
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Toll-like receptors can only exist as homodimers, not heterodimers.
Toll-like receptors can only exist as homodimers, not heterodimers.
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Study Notes
- Innate immunity is the non-specific first line of defense against damage and infections, ready from birth.
- It includes anatomical, physiological/chemical, phagocytic/endocytic, and inflammatory features.
Anatomical Features:
- Skin acts as a mechanical barrier and has an acidic environment and commensal microflora.
- Mucosal surfaces, such as the respiratory, digestive, and urinary tracts, have cilia, mucus, and secretions that hinder bacterial attachment and provide competition.
- Epithelial cells have tight junctions that limit entry.
Physiological/Chemical Features:
- The body maintains a core temperature of 37°C (98.6°F), which inhibits microbial growth.
- Chemical mediators and antimicrobial proteins/peptides (AMPs) are produced.
- Examples include lysozyme, lactoferrin, psoriasin, surfactant proteins, defensins, cathelicidins, histatin, dermicidin, and complement components.
Phagocytic/Endocytic Features:
- Phagocytosis is the process of cells internalizing and digesting foreign particles or pathogens.
- Receptor-mediated endocytosis specifically binds ligands, growth factors, hormones, or immune complexes to receptors.
- Phagocytic cells include neutrophils, monocytes/macrophages, dendritic cells, and eosinophils.
Inflammatory Features:
- Tissue damage or pathogen invasion triggers a response involving T/B effector cells and immune cells.
- Phagocytes release inflammatory mediators, such as cytokines and chemokines, to recruit other cells and initiate tissue repair.
- The complement system is activated, leading to the formation of the membrane attack complex (MAC) and opsonization.
- Pattern recognition receptors (PRRs), including toll-like receptors (TLRs) and other PRRs, recognize pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) to initiate an immune response.
Innate Immunity Defensive Barriers:
- Anatomical: Skin, mucosal surfaces, epithelial cells.
- Physiological/chemical: Temperature, chemical mediators, AMPs.
- Phagocytic/endocytic: Pinocytosis, receptor-mediated endocytosis, phagocytosis.
- Inflammatory: Cytokines, chemokines, complement system, PRRs.
Phagocytosis Mechanisms:
- Invagination of the plasma membrane to internalize extracellular material.
- Pinocytosis: Cell drinking to bring in nutrients and aid cellular osmoregulation.
- Macro-pinocytosis: Larger "gulps" that may play a role in membrane recycling.
- Receptor-mediated endocytosis: Specific uptake of ligands via receptor clustering and association with clathrin-coated pits.
Innate Immunity Cells:
- Phagocytes: Monocytes/macrophages, neutrophils, dendritic cells, and eosinophils.
- TLRs and other PRRs: C type lectin receptors, scavenger receptors, NLRs, RIG-like receptors, ALRs, and cGAS/STING.
Phagocytosis Stages:
- (1) Recognition: Direct (non-opsonic) or indirect (opsonic) binding of pathogens or particles to PRRs.
- (2) Ingestion: Cell surface receptors and cytoskeletal rearrangement lead to phagosome formation.
- (3) Digestion: Lysosomal enzymes degrade the engulfed material.
- (4) Exocytosis: The resulting vesicle, now called a lysosome, fuses with the plasma membrane to release its contents.
PRRs:
- Pattern recognition: Direct binding of pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs).
- Examples: LPS, Flagellin, glycoproteins, mannose/fucose/α mannan, β1-3 glucan, mannans, and phosphatidylserine.
- C type lectin receptors: Mannose Receptor, Dectin-1, and DC-SIGN.
- Scavenger receptors: SR-A and SR-B.
TLRs:
- Membrane-bound receptors that activate complex signaling pathways upon ligand binding.
- Toll gene discovered in Drosophila in 1996, TLR4 identified as LPS receptor in 1998.
- Function: Induce inflammatory responses and activate adaptive immunity.
- Examples: TLR1, TLR2, TLR3, TLR4, TLR5, TLR7, TLR8, TLR9, TLR11.
Intracellular TLRs:
- Detect viral DNA and RNA, inducing type I interferons.
- Examples: TLR3, TLR7, TLR8, TLR9.
Cell Surface TLRs:
- Expressed mostly by immune cells (MCs, MFs, DCs).
- Bind bacterial and fungal LPS and flagellin.
- Activate complex signaling pathways leading to inflammation.
NLRs, RIG-like receptors, ALRs, and cGAS/STING:
- Bind intracellular PAMPs and DAMPs.
- Activate the NF-κB pathway and autophagy.
- Induce production of cytokines and inflammatory responses.
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Description
Test your knowledge on antimicrobial peptides and proteins such as Psoriasin, Surfactant Proteins, and Defensins. Learn about their functions, mechanisms of action, and specificity against different pathogens.
