p.5
Regulation of Innate Immune Responses
What is the role of second signals in lymphocyte activation?
They work together with antigen recognition to activate lymphocytes.
p.1
Microbicidal Substances in Macrophages
What enzyme catalyzes the conversion of arginine to nitric oxide (NO) in macrophages?
Inducible nitric oxide synthase (iNOS).
p.1
Phagocytosis and Intracellular Killing
Where are microbicidal substances primarily produced in phagocytes?
In lysosomes and phagolysosomes.
p.2
Antiviral Defense Mechanisms
How do Type I IFNs help in treating chronic viral hepatitis?
They inhibit viral replication and destroy viral genomes.
p.1
Chronic Granulomatous Disease (CGD)
What is chronic granulomatous disease (CGD)?
An immunodeficiency disorder caused by a deficiency of phagocyte oxidase, preventing neutrophils from eradicating intracellular microbes.
p.9
Role of Innate Immunity in Adaptive Responses
How do innate immune responses enhance adaptive immunity?
Innate immune responses help activate and shape adaptive immunity by providing signals and cytokines that guide the development of adaptive immune cells, such as T and B lymphocytes, and by presenting antigens to these cells.
p.2
Chronic Granulomatous Disease (CGD)
What are granulomas?
Collections of activated macrophages around microbes.
p.1
Microbicidal Substances in Macrophages
What is the role of lysosomal proteases in macrophages?
They break down microbial proteins.
p.3
Regulation of Innate Immune Responses
What are SOCS proteins and their role in inflammation?
Suppressors of cytokine signaling (SOCS) block the responses of cells to various cytokines, including IFNs.
p.5
Regulation of Innate Immune Responses
What are adjuvants used for in vaccination?
To elicit innate immune reactions similar to those caused by microbes.
p.5
Regulation of Innate Immune Responses
How do B lymphocytes get activated during infection?
By recognizing microbial antigens and C3d bound to the microbes.
p.2
Microbicidal Substances in Macrophages
What role do macrophages play in tissue repair?
They produce growth factors that stimulate tissue cell and fibroblast proliferation.
p.5
Regulation of Innate Immune Responses
What are costimulators for T cells?
Substances like B7-1 (CD80) and B7-2 (CD86) that enhance T cell activation.
p.5
Regulation of Innate Immune Responses
What is the significance of C3d in B cell activation?
It acts as a second signal for humoral immune responses.
p.5
Role of Innate Immunity in Adaptive Responses
What type of immunity is needed to eliminate intracellular and phagocytosed microbes?
Cell-mediated immunity mediated by T lymphocytes.
p.2
Antiviral Defense Mechanisms
What is the function of Type I interferons (IFNs) in antiviral defense?
They inhibit viral replication and induce an antiviral state in cells.
p.2
Type I Interferons (IFNs)
Which cells are a major source of Type I IFNs?
Plasmacytoid dendritic cells.
p.1
Neutrophil Extracellular Traps (NETs)
What are neutrophil extracellular traps (NETs)?
Networks of chromatin extruded by dying neutrophils that trap and kill microbes.
p.8
Microbial Evasion of Innate Immunity
What are examples of microbial substances recognized by the innate immune system?
Examples include lipopolysaccharides (LPS) and peptidoglycan.
p.2
Antiviral Defense Mechanisms
What is the role of NK cells in viral infections?
They destroy virus-infected cells.
p.1
Microbial Evasion of Innate Immunity
What happens to tissues during inflammation caused by neutrophils?
Enzymes and reactive oxygen species (ROS) can injure host tissues.
p.4
Microbial Evasion of Innate Immunity
What is the function of catalase in immune responses?
Catalase breaks down reactive oxygen intermediates.
p.2
Regulation of Innate Immune Responses
What regulatory mechanisms help prevent excessive tissue damage during immune responses?
Production of anti-inflammatory cytokines like IL-10 by macrophages and dendritic cells.
p.3
Microbial Evasion of Innate Immunity
How do microbes evade innate immunity?
Through mechanisms such as resistance to phagocytosis and resistance to reactive oxygen intermediates.
p.7
Antiviral Defense Mechanisms
What is the function of natural killer (NK) cells?
They kill host cells infected by intracellular microbes and produce interferon-γ (IFN-γ).
p.8
Phagocytosis and Intracellular Killing
How do phagocytes ingest and kill microbes?
Phagocytes engulf microbes through phagocytosis and kill them using reactive oxygen species (ROS) and enzymes.
p.6
Regulation of Innate Immune Responses
What do all multicellular organisms possess to defend against infections?
Intrinsic mechanisms of defense known as innate immunity.
p.6
Microbial Evasion of Innate Immunity
What receptors does the innate immune system use to sense microbes?
Germline-encoded membrane and cytosolic receptors.
p.6
Cytokines and Their Functions in Immunity
What responses are primarily associated with innate immunity?
Inflammation and the antiviral state.
p.4
Microbial Evasion of Innate Immunity
How does Listeria monocytogenes evade destruction inside phagocytes?
By producing a protein that enables it to escape from phagocytic vesicles into the cytoplasm.
p.6
Cytokines and Their Functions in Immunity
What are inflammasomes?
Multiprotein complexes that generate active interleukin-1β in response to infection or cell injury.
p.6
Microbicidal Substances in Macrophages
What do epithelial cells provide against microbes?
Physical barriers and antimicrobial peptides.
p.3
Regulation of Innate Immune Responses
What inhibits the microbicidal functions of macrophages?
IL-1 receptor antagonist blocks the actions of IL-1.
p.1
Phagocytosis and Intracellular Killing
What occurs when a phagosome fuses with a lysosome?
The phagocyte becomes activated and kills ingested microbes.
p.3
Regulation of Innate Immune Responses
What mechanisms control inflammasome activation?
Posttranslational modifications like ubiquitination and phosphorylation, along with certain micro-RNAs.
p.2
Antiviral Defense Mechanisms
What is the effect of inherited deficiency of Type I IFNs related to COVID-19?
It is associated with severe cases of the disease.
p.3
Antiviral Defense Mechanisms
What are Type I interferons (IFNs) and their source?
Type I IFNs (IFN-α, IFN-β) are produced by plasmacytoid dendritic cells and virus-infected cells.
p.7
Phagocytosis and Intracellular Killing
How do phagocytes destroy microbes?
By engaging different receptors and ingesting them.
p.8
Cytokines and Their Functions in Immunity
What is the inflammasome?
A multiprotein complex that activates inflammatory responses.
p.1
Microbicidal Substances in Macrophages
What substances kill microbes inside phagocytes?
Reactive oxygen species (ROS), nitric oxide (NO), and lysosomal enzymes.
p.7
Cytokines and Their Functions in Immunity
What do innate lymphoid cells (ILCs) secrete?
Various cytokines that induce inflammation.
p.6
Role of Innate Immunity in Adaptive Responses
What do blood-borne microbes need for combat?
Antibodies produced by B lymphocytes.
p.4
Microbial Evasion of Innate Immunity
What mechanism do streptococci use to evade complement activation?
M protein blocks C3 binding to the organism and C3b binding to complement receptors.
p.7
Cytokines and Their Functions in Immunity
What are some cytokines involved in innate immunity?
Tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6, and chemokines.
p.7
Phagocytosis and Intracellular Killing
How are phagocytes recruited to sites of infection?
They bind to endothelial adhesion molecules induced by cytokines TNF and IL-1 and migrate in response to chemoattractants.
p.8
Cytokines and Their Functions in Immunity
What are the roles of cytokines TNF, IL-1, IL-12, and type I IFNs in defense against infections?
They promote inflammation, enhance immune responses, and activate immune cells.
p.4
Microbial Evasion of Innate Immunity
What does the cell wall of mycobacteria inhibit?
The fusion of phagosomes containing ingested bacteria with lysosomes.
p.6
Phagocytosis and Intracellular Killing
What are the principal components of innate immunity?
Epithelial barrier cells, phagocytes, dendritic cells, mast cells, natural killer cells, cytokines, and plasma proteins.
p.7
Phagocytosis and Intracellular Killing
What are the principal phagocytes involved in innate immunity?
Neutrophils and monocytes/macrophages.
p.8
Microbial Evasion of Innate Immunity
What are the receptors for microbial substances recognized by the innate immune system?
Toll-like receptors (TLRs) and C-type lectin receptors (CLRs).
p.2
Antiviral Defense Mechanisms
What is autophagy in the context of viral infections?
The process by which cellular organelles containing viruses are engulfed and destroyed.
p.3
Antiviral Defense Mechanisms
What is the role of Type I IFNs in CTL-mediated killing?
They increase the infected cell’s susceptibility to CTL-mediated killing.
p.8
Cytokines and Their Functions in Immunity
How is the inflammasome stimulated?
By pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs).
p.4
Microbial Evasion of Innate Immunity
How does sialic acid expression help Neisseria meningitidis avoid the immune system?
It inhibits C3 and C5 convertases.
p.7
Microbicidal Substances in Macrophages
What is the complement system?
A family of proteins activated by microbes and antibodies that opsonize microbes for phagocytosis, stimulate inflammation, and lyse microbes.
p.8
Role of Innate Immunity in Adaptive Responses
What is the role of MHC molecules in the recognition of infected cells by NK cells?
MHC molecules present antigens that help NK cells identify and target infected cells.
p.8
Role of Innate Immunity in Adaptive Responses
What is the physiological significance of MHC recognition by NK cells?
It helps in distinguishing healthy cells from infected or abnormal ones.
p.6
Microbial Evasion of Innate Immunity
What are Toll-like receptors (TLRs) known for?
Recognizing different microbial products and activating inflammatory or antiviral responses.
p.4
Microbial Evasion of Innate Immunity
How do several viruses evade the host antiviral state?
By encoding proteins that block the induction of type I IFNs.
p.4
Role of Innate Immunity in Adaptive Responses
What are the two signals required for full activation of antigen-specific lymphocytes?
Antigen (signal 1) and innate immune responses (signal 2).
p.3
Antiviral Defense Mechanisms
How do Type I IFNs interfere with viral replication?
They induce expression of enzymes that inhibit viral protein translation, increase RNA degradation, and inhibit viral gene expression.
p.7
Phagocytosis and Intracellular Killing
What role do macrophages play in inflammation and tissue repair?
Some macrophages limit inflammation and initiate tissue repair.
p.6
Role of Innate Immunity in Adaptive Responses
What induces the second signals that stimulate T cell responses?
Microbes encountered and ingested by dendritic cells or macrophages.
p.8
Regulation of Innate Immune Responses
What are the mechanisms by which the epithelia of the skin and gastrointestinal tract prevent the entry of microbes?
These include physical barriers, antimicrobial peptides, and tight junctions.
p.6
Role of Innate Immunity in Adaptive Responses
What system is activated by blood-borne microbes that stimulates B cell activation?
The plasma complement system.
p.3
Microbial Evasion of Innate Immunity
What is the mechanism of resistance to reactive oxygen intermediates in certain microbes?
Staphylococci have developed mechanisms to resist reactive oxygen species in phagocytes.
p.4
Microbial Evasion of Innate Immunity
How does Pseudomonas resist antimicrobial peptide antibiotics?
By synthesizing modified LPS that resists the action of peptide antibiotics.
p.4
Microbial Evasion of Innate Immunity
What is the mechanism of immune evasion used by coronaviruses?
Chemical modifications of viral RNA to evade recognition by RNA sensors.
p.7
Antiviral Defense Mechanisms
What are type I interferons (IFNs) responsible for?
Mediating antiviral defense by inhibiting viral replication.
p.7
Role of Innate Immunity in Adaptive Responses
How do innate immune responses activate adaptive immunity?
By providing signals that work with antigens to activate B and T lymphocytes.
p.4
Role of Innate Immunity in Adaptive Responses
What are 'danger signals' in the context of the immune system?
Molecules generated by innate immune responses that alert the adaptive immune system.