Class 17 Innate Immunity Overview
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Questions and Answers

What is the primary role of basophils in the immune system?

  • Facilitation of allergic reactions and inflammation (correct)
  • Production of antibodies
  • Detection of viral infections
  • Phagocytosis of pathogens

Which of the following cells primarily are responsible for host defense and housekeeping in tissues?

  • Natural Killer Cells
  • Dendritic Cells
  • Monocytes (correct)
  • Basophils

What is one of the functions of cytokines in the immune system?

  • Directly kill infected cells
  • Facilitate communication between cells (correct)
  • Generate antibodies
  • Process viral RNA

What type of immunity are B-cells primarily associated with?

<p>Humoral immunity (D)</p> Signup and view all the answers

What does the term 'innate' refer to in the context of immune responses?

<p>Response that is present from birth (A)</p> Signup and view all the answers

Which cytokine is most associated with regulating immune responses and controlling viral infections?

<p>Interferon (B)</p> Signup and view all the answers

What complication can arise from the overproduction of cytokines in response to certain pathogens?

<p>Cytokine Storm (D)</p> Signup and view all the answers

What is the primary role of barriers in the innate immune system?

<p>To prevent entry of infectious agents (B)</p> Signup and view all the answers

What is the primary function of Dendritic Cells in the immune system?

<p>Acting as sentinel cells and presenting materials to other immune cells (C)</p> Signup and view all the answers

Which of the following is NOT an issue with the skin as a barrier?

<p>High permeability to pathogens (C)</p> Signup and view all the answers

How does the mucosal membrane function as both a barrier and a door?

<p>It sheds outer layers but remains moist for transport. (A)</p> Signup and view all the answers

Which immune cells are part of the innate immune response with the ability to kill infected or abnormal cells?

<p>Natural Killer Cells (C)</p> Signup and view all the answers

What is the primary purpose of the secretion of mucous in mucosal membranes?

<p>To facilitate movement of pathogens out of the body (B)</p> Signup and view all the answers

What type of agents do sensors in the innate immune response detect?

<p>Common pathogens and their signatures (B)</p> Signup and view all the answers

Which of the following correctly describes the outermost layer of skin?

<p>It is dead and keratinized to prevent pathogen entry. (C)</p> Signup and view all the answers

What type of substances do mucosal membranes secrete to help kill pathogens?

<p>Antimicrobial enzymes and peptides (A)</p> Signup and view all the answers

What is the primary function of lysozyme?

<p>Degrades peptidoglycan (B)</p> Signup and view all the answers

Which class of white blood cells is known for having a short lifespan, typically measured in hours?

<p>Neutrophils (A)</p> Signup and view all the answers

How do normal flora help prevent infections?

<p>By consuming available nutrients (C)</p> Signup and view all the answers

What role do defensins play in the immune response?

<p>Form pores in microbial membranes (C)</p> Signup and view all the answers

Which type of cell is primarily involved in clotting?

<p>Platelets (B)</p> Signup and view all the answers

What characteristic is unique to eosinophils?

<p>Their granules stain dramatically with eosin (A)</p> Signup and view all the answers

Which of the following is NOT a function attributed to normal flora?

<p>They act as white blood cells (B)</p> Signup and view all the answers

What type of white blood cell has a nucleus that fills most of the cell?

<p>Lymphocytes (A)</p> Signup and view all the answers

What is the primary role of cytokines in the inflammatory response?

<p>To mark the area of infection and attract help. (D)</p> Signup and view all the answers

Which of the following terms refers to inflammation?

<p>Itis (A)</p> Signup and view all the answers

How do blood vessels respond during inflammation?

<p>They become leaky and increase in size. (B)</p> Signup and view all the answers

Which of the following is a symptom commonly associated with the body's inflammatory response?

<p>Pus formation (D)</p> Signup and view all the answers

What can excessive inflammation lead to in the case of a blood infection?

<p>Systemic inflammation and shock. (B)</p> Signup and view all the answers

Chronic inflammation can be caused by all the following EXCEPT?

<p>Acute viral infection (A)</p> Signup and view all the answers

What is a cytokine storm?

<p>Excessive release of cytokines leading to systemic inflammation. (C)</p> Signup and view all the answers

What effect do proinflammatory cytokines have on the body’s thermostat?

<p>They cause it to reset to a higher temperature. (B)</p> Signup and view all the answers

What is the primary function of the complement system?

<p>Amplifying immune responses against invaders (B)</p> Signup and view all the answers

Which of the following correctly describes the activation of the complement system?

<p>It involves cleaving C3 to initiate a cascade. (B)</p> Signup and view all the answers

What role do macrophages play in the immune system?

<p>They phagocytize and help recruit other immune cells. (A)</p> Signup and view all the answers

Which statement best describes the relationship between phagocytosis and macrophages?

<p>Macrophages perform phagocytosis as part of the immune defense. (B)</p> Signup and view all the answers

What is a possible outcome of the activation of C3b in the complement cascade?

<p>Promote opsonization of pathogens. (C)</p> Signup and view all the answers

What is the primary function of inactive viral proteins (iAVPs) when a cell is primed?

<p>Degrade all mRNA upon detection of a virus (D)</p> Signup and view all the answers

Which of the following triggers the complement system?

<p>Strange sugars and bound antibodies. (B)</p> Signup and view all the answers

Which receptors are responsible for detecting various microbial patterns?

<p>Pattern Recognition Receptors (PRRs) (D)</p> Signup and view all the answers

Which of the following is a common type of Pattern Recognition Receptor found in the membranes of sentinel cells?

<p>Toll-like Receptors (TLRs) (B)</p> Signup and view all the answers

What is the significance of granulomas in the immune response?

<p>They wall off organisms that may still be alive. (D)</p> Signup and view all the answers

How does the immune system control the complement cascade?

<p>Through multiple control and inactivation steps. (A)</p> Signup and view all the answers

What initiates the activation of iAVPs in a cell?

<p>Presence of a virus in the primed cell (B)</p> Signup and view all the answers

Which of the following is not a type of damage-associated molecular pattern (DAMP)?

<p>Peptidoglycan (C)</p> Signup and view all the answers

Where are cytoplasmic pattern recognition receptors (PRRs) primarily classified?

<p>By RIG-like and NOD-like receptors (C)</p> Signup and view all the answers

Which type of TLRs would be responsible for monitoring the extracellular environment?

<p>Surface TLRs (A)</p> Signup and view all the answers

What is one outcome of when a virus is detected in a primed cell?

<p>Induction of apoptosis in that cell (C)</p> Signup and view all the answers

Flashcards

Innate Immunity

The body's inborn defenses against common threats, existing from birth.

Barriers (Innate Immunity)

The body's first line of defense against invading pathogens, preventing entry.

Skin Barrier

Multiple layers of epithelial cells, creating a hard, waterproof barrier.

Mucosal Membranes

Membranes lining body openings, allowing transport but needing defenses.

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Mucosal Shedding and Washing

Mucosal membranes use shedding and mucus movement to remove pathogens.

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Antimicrobial Substances (Mucosa)

Enzymes and peptides in mucosal membranes that kill pathogens.

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First Line Defenses

The initial physical and chemical barriers against pathogen entry, like skin and mucous membranes.

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Adaptive Immunity

The acquired immune responses that develop after exposure to a pathogen, not present from birth

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Lysozyme function

Lysozyme degrades peptidoglycan, a component of bacterial cell walls.

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Peroxidases role

Peroxidases produce reactive oxygen species to kill microbes and break down hydrogen peroxide.

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Iron-binding proteins

Proteins like lactoferrin and transferrin bind iron, making it unavailable to microbes for growth.

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Defensins mechanism

Defensins (specialized defense peptides) form pores in microbial membranes, disrupting their structure and function.

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Neutrophils function

Neutrophils are white blood cells that phagocytose (engulf) microbes and kill them, or degranulate; a key part of pus.

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Eosinophils role

Eosinophils are white blood cells that stain with eosin and use granules to defend against pathogens.

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Normal flora role

Normal flora competes with pathogens for resources and produces toxic compounds, preventing pathogen growth.

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White blood cells types

White blood cells are categorized as granulocytes (with granules), mononuclear phagocytes (smooth nucleus), and lymphocytes (smaller cells, nucleus filling the cell).

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Histaminase

An enzyme found in granules of certain cells, particularly mast cells and basophils, that breaks down histamine.

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Basophils

White blood cells that contain granules filled with histamine and other inflammatory mediators, playing a role in allergic reactions and inflammation.

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Macrophages

Professional phagocytes that reside in tissues, engulfing and digesting pathogens and cellular debris, crucial for host defense and tissue maintenance.

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Dendritic Cells

Sentinel cells that patrol tissues, constantly gathering antigens and presenting them to other immune cells, initiating adaptive immune responses.

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B-cells

Lymphocytes responsible for humoral immunity, producing antibodies that target specific pathogens.

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T-cells

Lymphocytes responsible for cellular immunity, directly attacking infected cells or activating other immune cells.

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Natural Killer Cells

Lymphocytes that kill infected cells or tumor cells without prior sensitization, representing an innate defense mechanism.

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Cytokines

Small signaling molecules produced by cells that communicate with other cells, coordinating immune responses and influencing various cellular processes.

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iAVPs

Inactive viral proteins synthesized by neighboring cells to prime defenses against viruses.

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How do iAVPs get activated?

iAVPs are activated only when a virus is detected inside a primed cell.

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What does iAVP activation do?

Activated iAVPs trigger a cascade of responses in the infected cell: degradation of mRNA, halting protein synthesis, and ultimately programmed cell death (apoptosis).

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What are PRRs?

Pattern Recognition Receptors (PRRs) are specialized proteins that recognize specific patterns associated with microbes, pathogens, or cellular damage.

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What are MAMPs?

Microbe-associated molecular patterns (MAMPs) are molecules found on the surface of various microbes, indicating their presence.

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What are PAMPs?

Pathogen-associated molecular patterns (PAMPs) are molecules specific to pathogens, indicating a harmful infection.

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What are DAMPs?

Damage-associated molecular patterns (DAMPs) are signals released from damaged cells, indicating tissue injury or stress.

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Where are PRRs located?

PRRs can be found in different locations: on the cell surface, in phagosomes and endosomes, and even within the cytoplasm.

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PRRs & Cytoplasmic Markers

Pattern Recognition Receptors (PRRs) can identify specific molecules in the cytoplasm of cells, helping the immune system detect signs of infection or damage.

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Complement Cascade

A series of proteins (C1-C9) that work together in a chain reaction, called a cascade, to help fight infection. Precursor proteins are activated in a specific order, amplifying the immune response.

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What does the Complement Cascade do?

The Complement system has several key functions in fighting infection: it can "opsonize" (coat) pathogens, triggering phagocytosis by immune cells; it can trigger inflammation; and it can directly damage invading organisms.

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C3 protein

A key protein in the complement cascade. It can be cleaved into two parts: C3a which triggers inflammation, and C3b which opsonizes pathogens and activates further cascade steps.

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Phagocytosis

A process by which immune cells engulf and destroy pathogens or cellular debris. This is a key part of the innate immune response.

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Granulomas

Special structures formed by macrophages and lymphocytes to wall off infection. They can contain pathogens, but the organism may still be alive.

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Tuberculosis (TB) and Granulomas

TB can form granulomas in the lungs, which can interfere with lung function. This is because the bacteria may still survive inside the granuloma, even though it's walled off.

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Inflammation

A complex biological response to tissue damage, characterized by redness, swelling, heat, and pain, usually caused by infection or injury.

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What are Cytokines?

Small signaling molecules that coordinate immune responses by communicating between cells, attracting immune cells and promoting inflammation.

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What is Pus?

A thick, yellowish fluid formed during inflammation containing dead white blood cells, bacteria, and tissue debris.

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What are the effects of inflammatory mediators?

Inflammatory mediators like TNF, histamine, and others trigger blood vessel dilation (increasing blood flow), increased permeability (allowing fluid and cells to leave the bloodstream), and attract immune cells.

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What is 'itis'?

A suffix in medical terms indicating inflammation of a specific body part.

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What causes excessive inflammation?

Conditions like sepsis (blood infection), toxin-induced stimulation, or cytokine storms can lead to systemic inflammation, affecting the entire body.

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How does fever happen?

Proinflammatory cytokines signal the brain to raise the body's temperature (fever) as a defense mechanism against infection.

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Study Notes

Innate Immunity

  • Innate immunity is present from birth
  • It defends the body against common threats
  • Barriers prevent entry of infectious agents
  • Sensors detect signs of external agents
  • Effectors quickly respond to general threats

Barriers: Skin

  • Multiple layers of epithelial cells
  • Outermost layers are dead and keratinized
  • Hard for pathogens to penetrate
  • Hostile environment (arid, high salt)
  • External layer sheds, removing pathogens
  • Effective barrier in most cases
  • Issues with degradation from moisture
  • Mechanical abrasion or penetration
  • Penetration by specialized biochemistry (e.g., parasites)
  • Limited in nutrient/waste exchange

Barriers: Mucosal Membranes

  • Areas needing transport and moisture
  • Barriers and doors simultaneously
  • Contained spaces, making shedding difficult
  • Mucosal Membranes: Shed and Wash
  • Secrete sticky mucus
  • Move mucus to disposal areas
  • Shed cells along the way for additional defense

Mucosal Membrane – Antimicrobial Substances

  • Wide range of killing enzymes and peptides (e.g., lysozyme, peroxidases)
  • Break down hydrogen peroxide
  • Lactoferrin and transferrin bind iron (required for many microbes to grow)
  • Specialized defense peptides (HDPs)
  • Defensins form pores in microbial membranes

Recruiting Microbial Allies – Normal Flora

  • Competitive exclusion of pathogens
  • Consume available nutrients
  • Production of toxic compounds (e.g., fatty acids from Cutibacterium species)
  • Beneficial bacteria (e.g., E. Coli and lactobacilli) produce substances to protect from pathogens

Defenses in Blood and Lymph

  • Specialized cells derived from hematopoietic stem cells
  • Three general classes:
    • Red blood cells (erythrocytes): oxygen transport
    • Platelets (thrombocytes): clotting
    • White blood cells (leukocytes): body defenses

White Blood Cells

  • Originally categorized by microscopic appearance
  • Granulocytes (e.g., neutrophils, eosinophils, basophils)
  • Granules in the cytoplasm seen via specific stains
  • Mononuclear phagocytes (e.g., monocytes, macrophages, dendritic cells)
  • Smooth nucleus with clear cytoplasm
  • Lymphocytes (covered in a separate section)

Granulocytes (Neutrophils, Eosinophils, Basophils)

  • Neutrophils: short lifespan, major component of pus, kill by fusing with granules, attack by degranulating, increase with infection
  • Eosinophils: combat parasites and allergies
  • Basophils: contain histamine, roles in allergic reactions and inflammation

Mononuclear Phagocytes (Monocytes, Macrophages, Dendritic Cells)

  • Monocytes: circulate in blood, become macrophages in tissues, professional phagocytes, specialized by tissue, host defense, housekeeping
  • Macrophages: engulf and destroy pathogens
  • Dendritic cells: sentinel cells that collect material from wide area, present to other immune cells

Lymphocytes

  • Major part of adaptive immunity
  • Two primary subtypes (B-cells and T-cells) with similar appearance
  • B-cells: humoral immunity (antibodies)
  • T-cells: cellular immunity (attack infected cells)
  • Natural Killer cells: innate ability to kill certain types of cells

Cell Communication

  • Cytokines, chemokines, colony-stimulating factors (CSFs), interferons (IFNs), interleukins (ILs), tumor necrosis factor (TNF)
  • Cytokine storms: overproduction of cytokines in response to certain pathogens

What Triggers a Response?

  • Pattern Recognition Receptors (PRRs) recognize indicators of attack (Microbes, Pathogens, Damage):
    • Pathogen-associated molecular patterns (PAMPs)
    • Damage-associated molecular patterns (DAMPs)
    • Microbe-associated molecular patterns (MAMPs)

PRRs in Cytoplasm

  • Book classifies PRRs by "RIG-like" (RLRs) and "NOD-like" (NLRs)
  • Function to detect and identify markers of microbial and cellular damage

Soluble Enzymes in a Cascade

  • Required proteins are often present in inactive precursors
  • Multiple activation steps amplifying the response rapidly

Complement

  • Consisting of multiple proteins working together (C1-C9)
  • Initiated by multiple triggers including invading microorganisms, lectins, and antibodies
  • Potential effects include opsonization, inflammation, and membrane punching

Phagocytosis

  • Phagocytes "eat" by grabbing suspicious material
  • Surround the material with pseudopods
  • Direct lysosomes to fuse, digesting contents
  • Phagocytosis is essential for debris removal

Macrophages

  • Professional phagocytes
  • Pick up everything: dead cells, trash, invaders
  • Live for weeks/months
  • Alert and recruit other immune cells
  • Granulomas to wall off disease-causing agents

Inflammatory Response

  • PRRs (or complement) detect invaders
  • Cytokines mark the area, attract help (neutrophils)
  • Cause blood vessels to increase in size and become leaky to allow movement of leukocytes into tissue
  • Stimulates adhesion molecules on epithelial cells
  • Usually controlled but some areas are more sensitive to inflammation

Inflammation (-itis)

  • "-itis" suffix means inflammation
  • Examples: gastritis, meningitis, otitis media, gingivitis
  • Common symptoms like swelling and redness are caused by inflammatory mediators

Excessive Inflammation

  • Blood infections (sepsis) can lead to systemic inflammation ("shock")
  • Toxins induced stimulation
  • Cytokine storm
  • Chronic inflammation is part of several conditions (e.g., Rheumatoid Arthritis) or chronic stress, obesity, excessive red meat

Fever

  • Proinflammatory cytokines reset the body's thermostat to a higher temperature
  • Inhibit microbial growth, increase metabolism of immune cells, and increase efficiency of antimicrobial enzymes

Homework: Macrophages and Tattoos

  • Investigate the link between macrophages and tattoos,
  • Assess the net effect on the structure and duration of the tattoo, and
  • Provide a citation.

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Innate Immunity Class Notes PDF

Description

Explore the basics of innate immunity, which provides the body's first line of defense from birth. Learn about the crucial barriers like skin and mucosal membranes that prevent infection, as well as the mechanisms involved in detecting and responding to threats. This quiz will help reinforce your understanding of how these innate defenses function.

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