Innate Immunity Overview

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the innate immune response?

Defensive mechanisms that are active prior to infection and respond rapidly. It plays a crucial role in activating the adaptive immune response.

What is the adaptive immune response?

The adaptive immune response is inducible or tailor-made, involving T and B cells.

Describe the diversity of the innate immune response.

The innate immune response has a limited number of conserved germline-encoded receptors.

What is the diversity of the adaptive immune response?

<p>The adaptive immune response is highly diverse, with a very large number of receptors arising from genetic recombination of receptor genes in each individual.</p> Signup and view all the answers

Does the innate immune response have memory?

<p>The innate immune response has some memory in NK cells.</p> Signup and view all the answers

How does the innate immune response discriminate between self and non-self?

<p>The innate immune response is perfect in its discrimination between self and non-self. There are no microbe-specific self/non-self patterns in the host.</p> Signup and view all the answers

How does the adaptive immune response discriminate between self and non-self?

<p>The adaptive immune response is very good at self/non-self discrimination. Occasional failures of discrimination can result in autoimmune disorders.</p> Signup and view all the answers

What are the soluble components of the innate immune response found in blood?

<p>Antimicrobial peptides, proteins, and mediators are soluble components of the innate immune response in blood.</p> Signup and view all the answers

What are the soluble components of the adaptive immune response found in blood?

<p>Antibodies and cytokines are soluble components of the adaptive immune response in blood.</p> Signup and view all the answers

List the major cell types of the innate immune response.

<p>The major cell types of the innate immune response include phagocytes (monocytes, macrophages, neutrophils, NK cells, other leukocytes, epithelial, and endothelial cells), and dendritic cells.</p> Signup and view all the answers

What are the major cell types of the adaptive immune response?

<p>The major cell types of the adaptive immune response include T cells, B cells, and antigen-presenting cells (APCs). B cells can also serve as APCs.</p> Signup and view all the answers

What are chemokines?

<p>Chemokines are smaller cytokines specialized in directing cell movement, acting like breadcrumbs leading to infection sites.</p> Signup and view all the answers

What is the function of cytokines?

<p>Cytokines are involved in cell-to-cell communication and are essential for coordinating immune responses.</p> Signup and view all the answers

Which of the following are types of Innate Lymphoid Cells (ILCs)? (Choose all that apply)

<p>ILC3 (A), ILC1 (B), Natural Killer Cells (C), ILC2 (D)</p> Signup and view all the answers

What is the function of Innate Lymphoid Cells (ILCs)?

<p>ILCs recognize broad patterns and act like T cells until T cells can clonally expand. ILCs can already do much of what differentiated T cells can do to gain an early advantage.</p> Signup and view all the answers

How does the skin act as a barrier in the innate immune system?

<p>The skin serves as a barrier with several mechanisms: shedding outer layers removes attached organisms, slightly acidic pH (5-6) inhibits growth, high salt concentration is unfavorable, periodic drying discourages growth, and non-specific chemicals like psoriasin are present.</p> Signup and view all the answers

What factors can impact the effectiveness of physical barriers in the innate immune system?

<p>Direct factors like nutrition, physiology, fever, age, and genetics, as well as indirect factors like hygiene, socioeconomic status, and living conditions can impact physical barriers.</p> Signup and view all the answers

How do physiological factors contribute to the innate immune response?

<p>Physiological factors like fever are part of the innate immune system and function to slow down bacterial and viral replication. Macrophages release inflammatory cytokines (IL-1, IL-6, and TNF-α) to induce fever, which also makes macrophages more effective at phagocytosis.</p> Signup and view all the answers

Explain the concept of cell communication in the context of the immune response.

<p>For a cell to respond to a cytokine, it must have the receptor that is able to recognize that cytokine. It requires both the cytokine and its corresponding receptor. Different cell types can have different cytokine receptors, allowing for specific responses to different stimuli.</p> Signup and view all the answers

Define phagocytosis.

<p>Phagocytosis is the process by which phagocytic cells recognize, ingest, and kill extracellular microbes.</p> Signup and view all the answers

List the major cell types that are phagocytic.

<p>Monocytes, tissue macrophages, dendritic cells, and neutrophils are phagocytic cells.</p> Signup and view all the answers

Explain how phagocytosis helps with cell communication.

<p>Phagocytosis helps cellular communication by breaking pathogens into 'breadcrumbs' that attract other phagocytic cells. Some of these 'breadcrumbs' are attached to MHC molecules, which can be presented to T cells.</p> Signup and view all the answers

How does phagocytosis occur?

<p>Phagocytosis occurs through the recognition of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Phagocytic cells have receptors that bind to these molecules.</p> Signup and view all the answers

What are pathogen-associated molecular patterns (PAMPs)?

<p>PAMPs are cell wall components, such as mannan, β-glucan, lipopolysaccharide, peptidoglycan, and proteins.</p> Signup and view all the answers

What are monocytes?

<p>Monocytes are macrophages that are present in the blood. When they travel to tissues, they differentiate into specialized tissue macrophages.</p> Signup and view all the answers

How does phagocytosis clear cellular debris?

<p>Phagocytosis is crucial for clearing dead cells through the recognition of danger-associated molecular patterns (DAMPs).</p> Signup and view all the answers

What are DAMPs?

<p>DAMPs are danger-associated molecular patterns. Cells undergoing cell death have plasma membrane inversions that expose molecules like annexins, phosphatidylserine, and altered carbohydrates, which are recognized by phagocytic cells.</p> Signup and view all the answers

Describe the two mechanisms of phagocytic recognition.

<p>Phagocytic recognition can occur through opsonin-independent and opsonin-dependent mechanisms.</p> Signup and view all the answers

What is an opsonin?

<p>Opsonins are molecules that bind to microorganisms and dead cells to form a 'tag' that can then be recognized by phagocytic cells.</p> Signup and view all the answers

Provide examples of opsonins.

<p>Examples of opsonins include complement components, mannose-binding lectin, C-reactive protein, and antibodies (produced by B cells).</p> Signup and view all the answers

All opsonins are components of the innate immune response.

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

How does opsonization affect phagocytosis?

<p>Opsonization significantly increases phagocytosis. The more tagging components (opsonins) are present, the higher the likelihood that the target will be recognized, internalized, and destroyed.</p> Signup and view all the answers

Can a random particle in the body be recognized by the immune system?

<p>Yes, even if there is no innate receptor recognizing a new molecule, the adaptive immune system can tailor a response to it.</p> Signup and view all the answers

What is MHC II and its importance?

<p>MHC class II is crucial for the activation of CD4 T cells, which are important for regulating the immune response.</p> Signup and view all the answers

The material released after phagocytosis (exocytosed degraded material) is a cytokine.

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

Some phagocytic cells are polymorphonuclear. What is an example?

<p>Neutrophils are an example of a polymorphonuclear phagocytic cell.</p> Signup and view all the answers

What are some oxidative mechanisms used by phagocytic cells to destroy pathogens?

<p>Phagocytic cells utilize bleach and peroxide, which are oxygen-requiring compounds, to destroy microorganisms.</p> Signup and view all the answers

What is a TLR (Toll-like Receptor)?

<p>A TLR is a toll-like receptor involved in recognizing pathogen-associated molecular patterns (PAMPs) but not always internalization. TLRs are essential for generating inflammatory responses.</p> Signup and view all the answers

Which cells perform endocytosis?

<p>Tissue macrophages, blood monocytes, neutrophils, eosinophils, and dendritic cells all perform endocytosis. Eosinophils are the only cell not included in the phagocytic example.</p> Signup and view all the answers

What is lysozyme?

<p>Lysozyme is an enzyme that hydrolyzes peptidoglycan, a major component of bacterial cell walls.</p> Signup and view all the answers

What is the function of lactoferrin/transferrin?

<p>Lactoferrin/transferrin are important for binding iron, which is an essential nutrient for bacteria.</p> Signup and view all the answers

What does calprotectin do?

<p>Calprotectin chelates zinc in Staphylococcus aureus, which is a common bacterial pathogen.</p> Signup and view all the answers

What is psoriasin?

<p>Psoriasin is an antimicrobial peptide produced by human skin and tongue that is effective against Escherichia coli.</p> Signup and view all the answers

What is the function of cationic peptides?

<p>Cationic peptides disrupt cell membranes, leading to cell death.</p> Signup and view all the answers

What are bacteriocins?

<p>Bacteriocins are peptides produced by normal microbiota, which can be lethal to related bacterial species.</p> Signup and view all the answers

What type of bacteriocins are produced by Escherichia coli?

<p>Escherichia coli produces colicins.</p> Signup and view all the answers

What are lantibiotics?

<p>Lantibiotics are antimicrobial peptides produced by a variety of Gram-positive genera.</p> Signup and view all the answers

Define complement.

<p>Complement is a series of proteins that act as an opsonin, enhancing the immune response.</p> Signup and view all the answers

What is complement composed of?

<p>Complement includes more than 30 serum proteins.</p> Signup and view all the answers

What are the major activities of complement?

<p>Complement primarily defends against bacterial infections, bridges innate and adaptive immunity, and disposes of cellular waste.</p> Signup and view all the answers

Why is complement named as such?

<p>Complement is named so because it augments (complements) the antibacterial activity of antibodies.</p> Signup and view all the answers

Describe the complement activation pathway.

<p>Complement activation begins in different ways, each with specific proteins, but they share the same outcomes. All pathways are activated as a cascade, where the activation of one protein initiates the activation of the next.</p> Signup and view all the answers

What are the major outcomes of complement activation?

<p>Complement activation leads to opsonization (tagging pathogens for destruction), stimulation of inflammatory mediators, and lysis (breaking down) of microbes.</p> Signup and view all the answers

What are the categories of interferons?

<p>Interferons are classified into three types: type I, type II, and type III.</p> Signup and view all the answers

What is the general function of interferons?

<p>Interferons induce an antiviral state within cells, making them less susceptible to viral infection.</p> Signup and view all the answers

Which cells produce Type I interferons?

<p>Many cell types can produce Type I interferons (α, β, and τ), but Type I IFNs are mainly produced by virally infected cells.</p> Signup and view all the answers

What is IFN II?

<p>IFN II refers to a single interferon, IFNγ.</p> Signup and view all the answers

What cells primarily produce IFNγ?

<p>IFNγ is mainly produced by natural killer (NK) cells and T cells.</p> Signup and view all the answers

What is an inflammatory response?

<p>The inflammatory response is triggered by foreign substances. It involves capillary expansion (redness), increased vascular permeability (swelling), and leukocyte and plasma protein leakage (edema) to recruit immune cells and fight infection.</p> Signup and view all the answers

What type of antigens do CD4 T cells recognize?

<p>CD4 T cells recognize environmental antigens presented on MHC II.</p> Signup and view all the answers

What is the main cell type responsible for humoral immunity?

<p>B cells are the primary cellular component of humoral immunity, responsible for producing antibodies.</p> Signup and view all the answers

What are the main cell types involved in cellular immunity?

<p>T cells, particularly CD4 and CD8 T cells, are the key players in cellular immunity.</p> Signup and view all the answers

What cells bridge innate and adaptive immunity?

<p>Natural killer cells and γδ (gamma delta) T cells bridge innate and adaptive immunity.</p> Signup and view all the answers

List the major cell types of the innate immune system.

<p>Granulocytes (basophils, eosinophils, neutrophils), mast cells, NK cells, complement proteins, macrophages, and dendritic cells are all part of the innate immune system.</p> Signup and view all the answers

What cells are considered granulocytes?

<p>Basophils, eosinophils, and neutrophils are all categorized as granulocytes.</p> Signup and view all the answers

Define an antigen.

<p>An antigen is any substance that can elicit an immune response. Similar compounds often trigger the production of distinct and highly specific antibodies.</p> Signup and view all the answers

What are B cells?

<p>B cells are the only cells that can make antibodies, which are essential for humoral immunity.</p> Signup and view all the answers

What receptor do B cells have on their surface?

<p>B cells have a B cell receptor (BCR) on their surface, essentially a transmembrane antibody.</p> Signup and view all the answers

How do B cells and T cells differ in terms of antigen recognition?

<p>B cells can recognize a wider range of antigens, including proteins, carbohydrates, lipids, and nucleic acids. T cells primarily recognize proteins and peptides.</p> Signup and view all the answers

What does a B cell express on its surface, and why is it important?

<p>B cells express MHC class II, which presents antigens to CD4 T cells. This is essential for the activation and differentiation of B cells into antibody-producing cells.</p> Signup and view all the answers

How do CD4 T cells help B cells?

<p>CD4 T cells help B cells produce the right isotype of antibodies, tailored to the specific antigen.</p> Signup and view all the answers

What are the light and heavy chains of a B cell, and what is their role?

<p>The light and heavy chains of a B cell contribute to the recognition of the antigen. They form the antigen-binding site of the antibody, determining the specificity of the antibody.</p> Signup and view all the answers

What is the tissue distribution of MHC class I?

<p>MHC class I is expressed on virtually every nucleated cell within the body.</p> Signup and view all the answers

What is the function of MHC class I?

<p>MHC class I is involved in the recognition of foreign antigens on infected cells by CD8 T cells.</p> Signup and view all the answers

What are the three cytokines often referred to as the 'inflammatory trio'?

<p>IL-1, IL-6, and TNF-α are often referred to as the 'inflammatory trio'.</p> Signup and view all the answers

Outline the steps involved in the process of phagocytosis.

<p>Phagocytosis involves the following steps: 1) Pseudopods engulf bacteria; 2) Bacteria enters the phagosome; 3) Lysosome fuses with the phagosome to create the phagolysosome; 4) Lysosome components degrade bacteria; 5) Degraded bacteria are presented on MHC II to T cells.</p> Signup and view all the answers

How are antibodies secreted from the body?

<p>Antibodies are secreted as soluble proteins, allowing them to circulate in the blood and lymph to reach target pathogens.</p> Signup and view all the answers

Flashcards

Innate Immune response

Defensive mechanisms active prior to infection that respond rapidly and aid in activating the adaptive response.

Adaptive immune response

Inducible or tailor-made immune response involving T and B cells.

Innate immune diversity

Limited number of conserved, germline-encoded receptors in the innate immune system.

Adaptive immunity diversity

Highly diverse with a large number of receptors from genetic recombination of receptor genes.

Signup and view all the flashcards

Innate immune memory

Memory present in natural killer (NK) cells.

Signup and view all the flashcards

Self/nonself discrimination in innate immunity

Perfect discrimination, no microbe-specific patterns in the host.

Signup and view all the flashcards

Self/nonself discrimination in adaptive immunity

Very good but can occasionally fail, resulting in autoimmune responses.

Signup and view all the flashcards

Phagocytosis

Process by which phagocytic cells recognize, ingest, and kill extracellular microbes.

Signup and view all the flashcards

Pathogen Associated Molecular Patterns (PAMPs)

Patterns recognized by innate immunity, such as cell wall components and proteins.

Signup and view all the flashcards

DAMPs

Danger Associated Molecular Patterns from dying or dead cells, signaling for immune response.

Signup and view all the flashcards

Opsonization

The process of marking pathogens for phagocytosis by binding molecules known as opsonins.

Signup and view all the flashcards

Complement system

A group of proteins that enhance (complement) immune responses, particularly inflammation and opsonization.

Signup and view all the flashcards

Interferon function

Cytokines that induce an antiviral state in neighboring cells.

Signup and view all the flashcards

CD4 T Cells

T helper cells that recognize MHC II and assist in activating B cells.

Signup and view all the flashcards

B Cells

The only cells that produce antibodies, crucial for the humoral immune response.

Signup and view all the flashcards

Antigen

Any substance that elicits an immune response, triggering antibody formation.

Signup and view all the flashcards

Lysozyme

An enzyme that hydrolyzes peptidoglycan, found in secretions and used for preventing bacterial growth.

Signup and view all the flashcards

Phagocytosis process

  1. Pseudopods engulf bacteria, 2) Bacteria is enclosed in a phagosome, 3) Lysosome fuses to form phagolysosome, 4) Bacteria is degraded and presented on MHC II.
Signup and view all the flashcards

Cationic peptides

Small proteins that disrupt bacterial cell membranes, playing a role in innate immunity.

Signup and view all the flashcards

Chemokines

Smaller cytokines that guide immune cells to sites of infection, acting like breadcrumbs.

Signup and view all the flashcards

MHC Class I

Molecule found on nearly all nucleated cells that presents antigens to CD8 T cells.

Signup and view all the flashcards

MHC Class II

Molecule found on antigen-presenting cells (APCs) that presents fragments to CD4 T cells.

Signup and view all the flashcards

Inflammatory response

Triggered by foreign substances, causes capillary expansion and increased permeability, allowing immune cell access.

Signup and view all the flashcards

Memory T cells

Long-lived T cells that remember past infections and respond quickly upon re-exposure.

Signup and view all the flashcards

Natural Killer (NK) Cells

Innate lymphoid cells that recognize stressed cells and kill them without prior sensitization.

Signup and view all the flashcards

Adaptive immunity

The part of the immune system that adapts its response to specific pathogens, involving T and B cells.

Signup and view all the flashcards

Granulocytes

A type of white blood cell with granules in its cytoplasm, including basophils, eosinophils, and neutrophils.

Signup and view all the flashcards

Eosinophils

A type of granulocyte involved in combating parasites and allergic reactions.

Signup and view all the flashcards

Monocytes

White blood cells that differentiate into macrophages and dendritic cells upon entering tissues.

Signup and view all the flashcards

Study Notes

Innate Immunity

  • Innate immunity is a rapid, pre-existing defense system
  • It plays a role in activating the adaptive immune response
  • Innate immunity has limited diversity, relying on conserved, germline encoded receptors
  • It lacks memory
  • Self/non-self discrimination is perfect in innate immunity
  • Innate immunity includes antimicrobial peptides, proteins, and mediators in blood
  • Major cell types include phagocytes (monocytes, macrophages, neutrophils, NK cells, leukocytes, epithelial & endothelial cells), and dendritic cells
  • Physical barriers like skin (pH, NaCl, drying, chemicals) play a role
  • Physiological factors like fever (cytokines like IL-1, IL-6, TNF-α) slow microbial replication
  • Cell communication is key, and cytokines (e.g., chemokines) direct cell movement and action.
  • Innate lymphoid cells (ILCs) include ILC1, ILC2, ILC3, and NK cells, aiding in innate immunity and initiating responses before adaptive response

Adaptive Immunity

  • Adaptive immunity is tailor-made and inducible, involving T and B cells
  • Highly diverse, utilizing genetic recombination for receptor generation
  • Adaptive immunity has good self/non-self discrimination, though errors cause autoimmunity
  • Adaptive immunity components include antibodies and cytokines in blood
  • Major cells are T cells, B cells, and antigen-presenting cells
  • B cells make antibodies
  • T cells (CD4 and CD8) participate in cellular responses

Phagocytosis and Antigen Presentation

  • Phagocytosis is the ingestion and killing of external microbes by phagocytic cells (monocytes, macrophages, dendritic cells, neutrophils)
  • Recognition involves both pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) receptors.
  • Opsonization enhances phagocytosis via molecules binding to microbes (complement, mannose-binding lectin, C reactive protein, antibodies)
  • Phagocytosis clears pathogens, cellular debris (via DAMPs) to signal other inflammatory cells, and present antigens via MHCII for T-cell recognition
  • Phagocytic cells release signaling molecules and help with cellular communication, as well as degrade bacteria within phagolysosomes.
  • Lysozyme, lactoferrin/transferrin, calprotectin, psoriasin, and cationic peptides are antimicrobial mechanisms
  • Antibodies also help in phagocytosis

Antigen Presentation and T cell Recognition

  • MHC Class I molecules present antigens to CD8 T cells (on virtually all nucleated cells).
  • MHC Class II molecules display antigens to CD4 T cells (usually on macrophages, B cells, and dendritic cells).
  • Antigen processing and presentation are vital for adaptive immune responses
  • CD4 T cells assist B cells by directing antibody class switching

Cytokines and Interferons

  • Interleukins (e.g., IL-1, IL-6, TNF-α) are important inflammatory signaling molecules
  • Interferons (IFNs) - Type I (α, β, Ï„) and Type II (γ) - are crucial for antiviral responses.
  • Cytokines communicate between immune cells.

Complement System

  • Complement is an opsonin system composed of over 30 serum proteins
  • It's involved in defense against bacteria, bridging innate and adaptive immunity, and disposing of waste.

Inflammatory Response

  • Inflammatory response triggers due to foreign substances, increasing blood flow, and vascular permeability, facilitating leukocyte/protein exit, causing swelling.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser