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Questions and Answers
Which of the following is NOT a characteristic of innate immunity?
Which of the following is NOT a characteristic of innate immunity?
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Pattern recognition receptors (PRRs) recognize both pathogen-associated molecular patterns (PAMPS) and damage-associated molecular patterns (DAMPS)
Pattern recognition receptors (PRRs) recognize both pathogen-associated molecular patterns (PAMPS) and damage-associated molecular patterns (DAMPS)
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What is the primary role of Type 1 interferons in the innate immune response?
What is the primary role of Type 1 interferons in the innate immune response?
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TLR-4 recognizes bacterial ______.
TLR-4 recognizes bacterial ______.
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Which of the following Toll-like receptors is located in endosomes and detects double-stranded RNA (dsRNA)?
Which of the following Toll-like receptors is located in endosomes and detects double-stranded RNA (dsRNA)?
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Activation of NF-kB through TLR signaling results in which of the following?
Activation of NF-kB through TLR signaling results in which of the following?
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Which of the following is NOT a way that microbes can evade innate immunity?
Which of the following is NOT a way that microbes can evade innate immunity?
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Match the following receptors with their location:
Match the following receptors with their location:
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Which of the following best describes the function of DAMPs?
Which of the following best describes the function of DAMPs?
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Type I interferons (IFN-alpha and IFN-beta) promote viral replication.
Type I interferons (IFN-alpha and IFN-beta) promote viral replication.
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What is the process by which leukocytes move through the endothelial layer to reach the site of infection or injury?
What is the process by which leukocytes move through the endothelial layer to reach the site of infection or injury?
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The ______ gradient allows leukocytes to move towards the site of tissue damage or infection.
The ______ gradient allows leukocytes to move towards the site of tissue damage or infection.
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Match the cytokine category with the corresponding function.
Match the cytokine category with the corresponding function.
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Anti-inflammatory cytokines, such as IL-10 and TGF-beta, promote inflammation and tissue damage.
Anti-inflammatory cytokines, such as IL-10 and TGF-beta, promote inflammation and tissue damage.
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Describe the two signals required for lymphocyte activation.
Describe the two signals required for lymphocyte activation.
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Which of the following is NOT a function of epithelia in immunity?
Which of the following is NOT a function of epithelia in immunity?
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Which of the following is NOT a mechanism used by microbes to resist the complement pathway?
Which of the following is NOT a mechanism used by microbes to resist the complement pathway?
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Neutrophils are long-lived cells that function primarily in tissue repair.
Neutrophils are long-lived cells that function primarily in tissue repair.
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What is the function of the inflammasome?
What is the function of the inflammasome?
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Macrophages use _ to produce reactive nitrogen species for phagocytosis.
Macrophages use _ to produce reactive nitrogen species for phagocytosis.
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Match the following phagocytic cells with their primary functions:
Match the following phagocytic cells with their primary functions:
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Which of the following is NOT involved in the movement of neutrophils into infected tissue?
Which of the following is NOT involved in the movement of neutrophils into infected tissue?
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The alternative pathway of complement activation requires antibodies to initiate its response.
The alternative pathway of complement activation requires antibodies to initiate its response.
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What are the three steps in the process of phagocytosis after the microbe binds to the phagocyte receptor?
What are the three steps in the process of phagocytosis after the microbe binds to the phagocyte receptor?
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Which of the following is NOT a function of the complement system?
Which of the following is NOT a function of the complement system?
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Natural killer (NK) cells are activated when Class I MHC is present on a cell's surface.
Natural killer (NK) cells are activated when Class I MHC is present on a cell's surface.
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What is the primary role of C3b in the complement system?
What is the primary role of C3b in the complement system?
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The cytokines, TNF and IL-1, along with _______ help move neutrophils into infected tissues.
The cytokines, TNF and IL-1, along with _______ help move neutrophils into infected tissues.
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Match the following cytokines with their primary effect:
Match the following cytokines with their primary effect:
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During the process of leukocyte migration, what is the role of selectins?
During the process of leukocyte migration, what is the role of selectins?
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The acute inflammatory response only eliminates pathogens and does not participate in tissue repair.
The acute inflammatory response only eliminates pathogens and does not participate in tissue repair.
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What is the result of the formation of the membrane attack complex (MAC) on a pathogen membrane?
What is the result of the formation of the membrane attack complex (MAC) on a pathogen membrane?
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Study Notes
Innate Immunity
- Two main reactions to block microbial invasion: inflammation at infection site and antiviral defense
- Inflammation involves leukocyte and plasma protein accumulation, dead tissue clearance, and repair initiation
- Antiviral defense involves NK cells killing infected cells and type I interferons blocking host cell viral replication
Antigen Recognition
- Innate immunity has receptors encoded in germline DNA with fixed, identical receptors and can recognize broad conserved microbial patterns. Receptors do not discriminate self from non-self.
- Adaptive immunity has receptors undergoing somatic rearrangement and mutation, leading to high specificity for individual antigens.
PAMPS/DAMPS
- Pattern Recognition Receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs)
- PRRs initiate immune signaling
- DAMPs are self-derived molecules released during tissue damage or cellular stress
- PAMPS are microbial molecules like lipopolysaccharides and viral RNA.
Toll-Like Receptors (TLRs)
- Cell-surface TLRs recognize bacterial lipopeptides (TLR1, 2, 6), peptidoglycan (TLR2), LPS (TLR4), and bacterial flagellin (TLR5).
- Endosomal TLRs recognize double-stranded RNA (TLR3), single-stranded RNA (TLR7, 8), and CPG DNA (TLR9).
TLR Signaling
- TLR signaling can occur through NF-κB, activating transcription factors and triggering acute inflammation, or IFN regulatory factors, activating antiviral actions.
Cell Surface/Extracellular Receptors
- Toll-like receptors (TLRs) recognize various microbial structures (e.g., cell wall lipids).
- N-formylmethionine receptors recognize microbial peptides.
Cytosolic Receptors
- NOD-like receptors (NLRs) recognize pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs)
- RIG-I-like receptors (RLRs) recognize viral RNA.
- Cytosolic DNA sensors (CDSs) recognize microbial DNA.
- Lectin receptors recognize fungal glycans and mannose residues.
Endosomal Receptors
- TLRs detect partially digested organism antigens.
Inflammasome
- Multi-protein complex assembling in the cytosol in response to microbes or cell injury.
- Activates caspase-1, producing inflammatory cytokines.
Functions of Epithelia
- Act as a physical barrier by killing microbes with antibiotics like defensins and cathelicidins.
Neutrophils
- Produced in bone marrow, circulate in blood, and extravasate to tissues during inflammation.
- Rapid response, short-lived, phagocytic cells with enzyme-filled granules.
- Phagocytosis and reactive oxygen species production (respiratory burst).
Monocytes
- Have indented/horse-shoe shaped nuclei, phagocytic cells found in blood.
- Migrate into tissues and differentiate into macrophages.
Macrophages
- Differentiated from monocytes, found in various tissues and organs.
- Have different names in different organs (e.g., Kupffer cells in liver, microglia in brain).
- Involved in phagocytosis and tissue repair.
Complement Activation
- Pathways (classical, alternative, lectin) converge to cleave C3, opsonize pathogens, and form the membrane attack complex (MAC).
Natural Killer (NK) cells
- Activated by IL-12 from macrophages.
- Release IFN-γ to boost macrophage activity.
- Directly kill virally infected cells or tumor cells if MHC class I molecules are absent or reduced.
Innate Immunity Cytokines
- Dendritic cells, macrophages, mast cells, and natural killer (NID cells produce cytokines in response to microbes.
- Cytokines initiate inflammation and activate other immune cells.
Interleukin 6 (IL-6)
- Source: Macrophages, endothelial cells
- Target/Effect: T-cell proliferation, B-cell proliferation (also antibody-producing cells)
Interleukin 15 (IL-15)
- Source: Macrophages, others
- Target/Effect: T-cell proliferation, NK cell proliferation
Acute Inflammatory Response
- Eliminates pathogens, removes damaged tissue, and promotes tissue repair.
Leukocyte Migration
- Endothelial activation by cytokines (TNF, IL-1), causing leukocyte rolling, adhesion, diapedesis, and chemotaxis toward the site of injury/infection.
Type I Interferon Response
- Inhibits viral replication by inhibiting protein synthesis, degrading viral RNA, and preventing viral gene expression and viral assembly.
Microbial Evasion of Innate Immunity
- Resistance to phagocytosis (e.g., bacterial capsules hiding PAMPS).
- Resistance to ROS.
- Resistance to complement pathways.
Lymphocyte Activation
- Cooperation between innate and adaptive immune systems via signals
- Microbial antigen interaction with specific adaptive receptors & molecule induction from innate response (e.g., cytokines) driving lymphocyte proliferation and differentiation.
Cytokine Categories
- Include anti-inflammatory (TGF-β, IL-10), antiviral (type I IFNs), pro-inflammatory (IL-1, TNF), T/NK/B cell proliferation (IL-2, IL-15), macrophage activation (INF-γ).
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Description
Explore the fundamental principles of innate immunity, including its role in inflammation and antiviral defense mechanisms. Understand the significance of antigen recognition in both innate and adaptive immunity, focusing on the receptors involved and how they differentiate between self and non-self. This quiz will enhance your knowledge of immune responses and recognition patterns.
