Questions and Answers
Which of the following cells are phagocytic and play a role in the innate immune response?
Which cells are responsible for activating T cells in the adaptive immune response?
What is the function of cytokines in the immune response?
Which pathway is NOT part of the innate immune system?
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Natural Killer (NK) cells are primarily involved in the innate response to which type of infection?
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Which of these proteins is an acute phase protein?
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What is the primary role of antimicrobial peptides in the innate immune system?
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Which of the following cells release inflammatory mediators in response to parasites?
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What is the main characteristic difference between the innate and adaptive immune responses?
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Which of the following is NOT a role of inflammation in combating infections?
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Which of the following is a cardinal sign of inflammation?
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Which cells are the first to be attracted to the site of infection during acute inflammation?
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What leads to the accumulation of fluid and proteins at the infection site during inflammation?
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How do inflammatory cells find their way to the site of infection in the tissues?
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What happens when a pathogen evades or overwhelms the innate immune response?
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Which of the following cell types are considered professional phagocytes?
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Phagocytosis involves what key initial process?
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Which of these barriers serves to prevent infection by facilitating expulsion?
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Which of the following mechanisms directly involves the destruction of bacterial cell walls?
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Reactive Oxygen Intermediates (ROI) produced during phagocytosis include which of the following?
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Phagosome acidification is a step that precedes which of the following?
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Which component in the innate immune system serves to prevent pathogens from colonizing surfaces?
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Study Notes
Mechanisms of Innate Immunity
- Humoral elements are soluble molecules that contribute to the innate response:
- Cytokines: large group of proteins and glycoproteins that mediate cell-cell communication and orchestrate inflammatory and immune responses
- Produced by various cell types, including macrophages, natural killer (NK) cells, and dendritic cells (DCs)
- Examples: interferons, interleukins
Cellular Elements
- Macrophages (sentinel cells):
- Phagocytose microbes immediately
- Release inflammatory mediators (cytokines, lipid mediators, peptides) -> initiates inflammatory response
- Migrate to lymphatic tissue and activate lymphocytes (initiates adaptive response)
- Long-lived cells, undergo multiple rounds of phagocytosis
- Neutrophils:
- Recruited to infection site during inflammatory response
- Highly phagocytic but short-lived
- Dendritic cells (interdigitating):
- Phagocytose microbes
- Migrate to lymphatic tissue and activate T cells (adaptive response)
Antimicrobial Peptides
- Expressed by epithelial cells and neutrophils
- 29-35 amino acids long
- Widespread activity against microbes
- Bind to microbial membranes and form pores
- Some microbes alter cell surface to confer resistance against these peptides
Complement System
- Group of serum proteins
- Important innate mechanism (and adaptive)
- Complement proteins activated by 3 pathways:
- Classical pathway (Ab:Ag complex - adaptive response)
- MBL pathway (innate)
- Alternative (Innate)
- Form pores in target microbes, generate inflammatory mediators, 'activate' phagocytes
Natural Killer Cells
- Found in blood and tissues
- Recognize and kill virus-infected cells (and tumor cells)
- Innate response to viral infection
Mast Cells
- Found in tissues
- Release inflammatory mediators in response to parasites
Other Humoral Elements
- Acute phase proteins (e.g. CRP)
- Collectins (e.g. MBL)
- Lipid inflammatory mediators (e.g. prostaglandins, leukotrienes)
Innate Response
- Important defense system
- Utilizes many effector mechanisms
- Effector mechanisms are shared by adaptive response, making them more efficient
- Inflammation accompanies immune responses and is induced during innate response
Inflammation
- Local response of tissue to damage/infection
- Four roles in combating infections:
- Deliver additional immune effector molecules and cells to infection site
- Activate incoming immune cells
- Provide physical barrier preventing spread of infection
- Promote repair of injured tissue (non-immunological)
- Characterized by redness, heat, swelling, and pain
- These cardinal signs reflect changes in local vasculature:
- Increased vascular diameter -> increased blood flow (heat and redness)
- Increased vascular permeability -> fluid and proteins accumulating at infection site (swelling and pain)
Cellular Migration
- Cells find their way to infection site by following concentration gradient of inflammatory mediators (chemokines)
- During acute inflammation, first cells attracted to site are neutrophils, followed by monocytes (innate)
- In later stages, lymphocytes (adaptive) are also present at infection site
- Mechanisms of cellular migration: Inflammatory mediators produced by macrophages and mast cells 'activate' surrounding endothelium
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Description
This quiz covers the humoral elements of innate immunity, including cytokines and macrophages. Learn about the role of these cells and molecules in the immune response.
