Innate Immunity Overview
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Questions and Answers

What percentage of the total lymphocyte population do B cells represent?

  • 20-25%
  • 10-15% (correct)
  • 30-35%
  • 5-10%

Which marker is NOT typically associated with B cells?

  • CD3 (correct)
  • CD20
  • CD19
  • MHC II

What is the primary function of plasma cells?

  • Secrete antibodies (correct)
  • Destroy foreign pathogens
  • Process antigens
  • Activate T cells

What role do memory B cells play in the immune system?

<p>Recall foreign antigens for quicker responses (A)</p> Signup and view all the answers

What happens to MHC I expression in cells that are infected with viruses?

<p>It is suppressed (D)</p> Signup and view all the answers

What role do NK cells play in response to cancerous cells?

<p>They assist in tumor rejection (B)</p> Signup and view all the answers

In what circumstances is MHC I expression often suppressed?

<p>When cells are infected with viruses or become cancerous (A)</p> Signup and view all the answers

What is one of the vital functions of NK cells?

<p>Performing roles in viral immunity (A)</p> Signup and view all the answers

What is the primary function of macrophages in various tissues?

<p>Clearing pathogens and debris (B)</p> Signup and view all the answers

Which type of macrophage is specifically found in the liver?

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

Which statement accurately reflects the effect of viral infections on MHC I expression?

<p>Viral infections suppress MHC I expression (A)</p> Signup and view all the answers

How do macrophages primarily clear pathogens from tissues?

<p>Via phagocytosis (D)</p> Signup and view all the answers

In addition to clearing debris, what role do macrophages play in the immune response?

<p>Antigen presentation and activation of memory cells (C)</p> Signup and view all the answers

What specialized structure do macrophages use to engulf particles during phagocytosis?

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

What systemic features are commonly associated with inflammatory responses?

<p>Fever and raised inflammatory markers (C)</p> Signup and view all the answers

Which symptom is NOT typically associated with the 'flu-like' symptoms due to systemic inflammation?

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

What is the role of costimulatory molecules like MHC-II and B7 in the immune system?

<p>They encourage activation of the adaptive immune system (A)</p> Signup and view all the answers

Which of the following is a raised inflammatory marker associated with systemic inflammation?

<p>C-reactive protein (CRP) (B)</p> Signup and view all the answers

Which of these symptoms involves muscle and joint discomfort that can result from systemic inflammation?

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

What is the primary role of antibody molecules in opsonization?

<p>To enhance phagocytosis (D)</p> Signup and view all the answers

Which term is associated with the process of antibodies marking pathogens for engulfment?

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

Which statement correctly describes opsonization?

<p>It refers to the binding of antibodies to pathogens for removal (A)</p> Signup and view all the answers

What misconception might one have regarding opsonization and phagocytosis?

<p>They are the same process (D)</p> Signup and view all the answers

What is NOT a characteristic of opsonization?

<p>It directly destroys pathogens (D)</p> Signup and view all the answers

What structure extends from the plasma membrane of a phagocyte to engulf a microorganism?

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

What is the sac formed around a microorganism during ingestion called?

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

What happens to the pH inside the phagosome during the ingestion process?

<p>It decreases to about pH 4 (D)</p> Signup and view all the answers

What role do enzymes play in the phagosome membrane?

<p>They pump protons into the phagosome (B)</p> Signup and view all the answers

Which of the following best describes the function of phagocytes?

<p>To engulf and digest microorganisms (A)</p> Signup and view all the answers

Flashcards

Macrophages

Cells that consume and break down unwanted material, including pathogens, debris, and old cells.

Küpffer cells

Specialized macrophages found in the liver, filtering and destroying harmful substances in the blood.

What are systemic features of infection?

These are signs of a systemic inflammatory response. They can appear in the early stages of infection and are caused by elevated levels of immune signaling molecules like C-reactive protein and ferritin.

Alveolar macrophages

Macrophages found in the lungs, removing inhaled pathogens and debris.

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What are 'flu-like' symptoms?

A group of symptoms that typically appear during an infection, often related to inflammation and immune system activation.

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Osteoclasts

Macrophages found in bone, responsible for breaking down old bone tissue during bone remodeling.

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What are "inflammatory markers"?

These molecules like CRP and ferritin are released in response to infection. They signal to the immune system and can also be measured in blood tests to indicate illness.

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Microglial cells

Macrophages found in the brain, responsible for removing waste products and damaged neurons.

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What are costimulatory molecules?

Molecules on the surface of cells that enhance the activation of the adaptive immune system, making it respond faster and more effectively.

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Give examples of costimulatory molecules.

MHC-II and B7 are examples are examples of these molecules. They are crucial for T cell activation, a key part of the adaptive immune response.

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B cells

A type of white blood cell responsible for producing antibodies, which help fight infections.

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Plasma cells

Mature B cells that secrete antibodies.

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Memory B cells

B cells that remember specific antigens, allowing for faster and stronger immune responses upon re-exposure.

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B cell surface markers

Surface markers that identify B cells, including CD19, CD20, CD21, and MHC II.

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Humoral immunity

The arm of the immune system where antibodies are used to fight infection.

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Opsonization

The process of making a pathogen more recognizable to phagocytes (immune cells that engulf and destroy pathogens) by coating it with antibodies.

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Importance of Opsonization

Opsonization is a key mechanism of the immune system, enhancing the efficiency of phagocytosis.

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Antibodies and Opsonization

Antibodies are proteins that can bind to specific antigens (molecules on the surface of pathogens).

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Phagocytosis

Phagocytosis is the process where immune cells engulf and destroy pathogens.

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Opsonization vs. Phagocytosis

The term "phagocytosis" is specifically used for the engulfment process, while "opsonization" refers to the process of making the target more palatable for phagocytosis.

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Pseudopods

Finger-like projections of the cell membrane that extend outwards to engulf the target particle.

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Phagosome

A vesicle formed when the plasma membrane of a phagocyte surrounds a target particle.

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Acidification of the phagosome

The process of lowering the pH inside a phagosome by pumping protons (H+) into it.

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Proton pumps

Enzymes found in the membrane of the phagosome that pump protons (H+) inside, lowering the pH.

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Why is MHC I expression suppressed in infected cells?

MHC I molecules on the surface of infected cells or cancerous cells are suppressed, preventing the recognition of infected or cancerous cells by the immune system. This suppression helps the virus or cancer to evade immune detection and spread.

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What are NK cells?

NK cells, also known as natural killer cells, are a type of lymphocyte that can kill infected or cancerous cells without prior sensitization. They play a crucial role in the immune system's defense against viruses and tumors.

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How do NK cells combat viral infections and tumors?

NK cells can destroy cells that have suppressed MHC I expression, contributing to the immune system's ability to fight infections and cancer. This makes NK cells essential for viral immunity and tumor rejection.

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Are NK cells part of the innate or adaptive immune system?

NK cells are part of the innate immune system, which provides a rapid and non-specific response to infection or disease. NK cells can act without prior exposure to the specific pathogen or cancer cell, making them a critical first line of defense.

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How do NK cells contribute to viral immunity?

Viral infections can be controlled by NK cells because they recognize and kill virus-infected cells before the virus can replicate and spread throughout the body. This is vital for preventing the development of severe illness.

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Study Notes

Innate Immunity Lecture Notes

  • Innate immunity is the first line of defense against infections.
  • It's very fast, usually established within 4 hours of infection.
  • It's less efficient than adaptive immunity.
  • Innate immunity is non-specific.
  • It includes mechanical barriers (e.g., skin), chemical responses (e.g., stomach acid), cellular defenses (e.g., phagocytes), and inflammation.
  • Innate immunity components include phagocytes (e.g., neutrophils, macrophages, dendritic cells) which recognize and eliminate pathogens by phagocytosis.
  • Phagocytes identify pathogens by recognizing pathogen-associated molecular patterns (PAMPs) using pathogen recognition receptors (PRRs), such as Toll-like receptors.
  • Cells of innate immunity are activated via chemotaxis (chemical attraction) and adherence (attachment) to the pathogen.
  • Microbes are coated with opsonins (e.g. complement proteins and antibodies) to promote phagocyte attachment (opsonization).
  • Phagocytosis involves ingestion and digestion of microbes.
  • Lysosomal enzymes like lysozyme, lipases, and proteases break down microorganisms within phagocytic vesicles.
  • An oxidative burst produces toxic oxygen products to further kill microbes.
  • Myeloperoxidase converts chloride and hydrogen peroxide into hypochlorous acid, contributing to microbe killing.
  • The residual body (indigestible material) is discharged from the phagocyte.
  • Natural killer (NK) cells are part of the innate immune system.
  • NK cells do not require activation by specific antigens.
  • These cells can identify and destroy virus-infected cells or cancerous cells.
  • NK cells release toxic granules to induce apoptosis to infected cells.
  • The acute inflammatory response is part of innate immunity, localizing and containing the infection.
  • Features of the inflammatory response include vasodilation, increased vascular permeability, release of inflammatory mediators (e.g., bradykinins and prostaglandins), and microvascular coagulation.
  • Components that activate the response are innate immune cells, complement cascade, and proinflammatory cytokines.
  • MHC (Major histocompatibility complex) proteins (i.e., MHC I, and MHC II) are surface proteins displaying fragments of antigens on cells.
  • Phagocytes present processed antigens on MHC proteins to activate the adaptive immune system.
  • Adaptive immunity has a delayed response, requiring full pathogen recognition.
  • Adaptive immunity is more efficient and specific, including B and T lymphocytes and their associated specific antibodies.
  • PAMPs and DAMPs (Damage-associated molecular patterns) are used to identify pathogens and cellular damage.
  • NLRs (NOD-like receptors) detect PAMPs and DAMPs inside the cell and initiate inflammation.

Cellular Innate Immune Response

  • The cellular component involves specialized cells that recognize and eliminate pathogens.
  • Phagocytes (e.g., neutrophils, macrophages, dendritic cells) are crucial for this. They engulf (phagocytose) pathogens, processing and presenting antigens to stimulate the adaptive immune response.
  • Neutrophils are the most abundant type, playing a key role in acute inflammatory responses. Neutrophils, after arriving at the site of infection, efficiently phagocytose foreign material, bacteria, and damaged cells.
  • Macrophages reside in tissues, performing the same functions as neutrophils, but they are longer-lived and more efficient at presenting processed antigens, serving as crucial linking points between innate and adaptive immune responses.
  • Dendritic cells are also phagocytic cells, but their main role is to migrate to lymph nodes and present antigens to T lymphocytes, initiating adaptive immune responses.

Innate Immune Cells - Different Subtypes and Properties

  • Granulocytes (e.g., neutrophils, eosinophils, basophils) are characterized by granules in their cytoplasm.
  • Neutrophils – the dominant white blood cells during inflammation have a rapid response.
  • Eosinophils are primarily involved in responses to parasitic infections and some allergic reactions.
  • Basophils are involved in allergic responses.

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Innate Immunity I, II تفريغ PDF

Description

This quiz explores the fundamental concepts of innate immunity, which serves as the body's initial defense against infections. Topics include the mechanisms of action, the roles of phagocytes, and the differences between innate and adaptive immunity. Test your knowledge on how the immune system quickly responds to pathogens.

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