γδ T Cells Overview
55 Questions
0 Views

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 primary developmental pathway NKT cells follow before diverging during the DP stage?

  • B cell pathway
  • αβ T cell pathway (correct)
  • γδ T cell pathway
  • Macrophage pathway

Which receptor engagement can enhance the activation of NKT cells in addition to TCR engagement?

  • MHC Class II molecules
  • IL-12 or IL-18 receptors (correct)
  • CD1d molecules
  • CD4 and CD8 receptors

What is a key effector function of activated NKT cells?

  • Production of antibodies
  • Secretion of cytokines and chemokines (correct)
  • Phagocytosis of pathogens
  • Direct cytolytic activity

What type of molecules do NKT cell TCRs typically recognize?

<p>Glycolipids presented by CD1d (A)</p> Signup and view all the answers

Which statement best describes the nature of cytokines produced by NKT cells?

<p>They have powerful effects on αβ T cell differentiation. (A)</p> Signup and view all the answers

What is a primary characteristic that distinguishes gd T cells from ab T cells in terms of their development?

<p>gd T cells rearrange TCRgd genes earlier than ab T cells. (B)</p> Signup and view all the answers

During which stage of development do gd T cells start to be detected in humans?

<p>By 8 weeks gestation. (A)</p> Signup and view all the answers

What is one function of cytokines produced by gd T cell effectors?

<p>They activate NK cells and macrophages. (A)</p> Signup and view all the answers

Which type of cell do gd T cells NOT appear to have immunological memory?

<p>gd T cells. (D)</p> Signup and view all the answers

What role do fetal thymic stromal cells play in gd T cell development?

<p>They influence gd T cell generation and migration. (A)</p> Signup and view all the answers

How do NKT cells differ from typical CTL and NK cells after activation?

<p>NKT cells can secrete cytokines immediately upon activation. (C)</p> Signup and view all the answers

Which statement correctly describes the thymic selection processes for gd T cells?

<p>gd T cells undergo positive and negative thymic selections. (C)</p> Signup and view all the answers

What function does nitric oxide (NO) have in relation to activated gd T cells?

<p>It is an antimicrobial compound produced by epithelial cells. (A)</p> Signup and view all the answers

Which cells do NKT cells share characteristics with?

<p>Both CTL and NK cells. (D)</p> Signup and view all the answers

What is one of the key additional roles of gd T cells beyond cytokine production?

<p>They influence leukocyte trafficking and wound healing. (C)</p> Signup and view all the answers

What is a significant characteristic of gd T cells compared to ab T cells in their recognition of antigens?

<p>They can respond to a broader range of ligands, including non-protein antigens. (A)</p> Signup and view all the answers

In which anatomical locations are gd T cells predominantly found?

<p>Among epithelial cells of the skin and mucosal areas. (C)</p> Signup and view all the answers

How do gd T cells differ in activation response compared to conventional ab T cells?

<p>They respond more rapidly and can activate without conventional costimulation. (C)</p> Signup and view all the answers

What type of TCR structure do gd T cells express?

<p>TCR composed of TCRg and TCRd chains. (C)</p> Signup and view all the answers

What is one reason gd T cells are critical in host defense?

<p>They fill gaps in immune responses that are not recognized by myeloid cells. (B)</p> Signup and view all the answers

What type of factors do activated gd T cells secrete to stimulate epithelial cell activity?

<p>Keratinocyte growth factor (KGF) (A)</p> Signup and view all the answers

Which cell types are influenced by the cytokines produced by gd T cell effectors?

<p>NK cells and Macrophages (C)</p> Signup and view all the answers

What is not a feature of gd T cells according to their function?

<p>Capability for immunological memory (D)</p> Signup and view all the answers

Which developmental stage do gd T cells reach during human embryonic development?

<p>By 8 weeks in the fetal stage (C)</p> Signup and view all the answers

What population of T cells is generated from the same precursor as gd T cells?

<p>Ab T cells (B)</p> Signup and view all the answers

Which of the following best describes the activation of NKT cells?

<p>They can secrete cytokines immediately after activation. (C)</p> Signup and view all the answers

What role do fetal thymic stromal cells play in the development of gd T cells?

<p>They influence distinct waves of gd T cell development. (C)</p> Signup and view all the answers

What type of antigens can gd TCRs bind directly, without the need for presentation by other molecules?

<p>Non-peptide antigens (B)</p> Signup and view all the answers

Which statement accurately describes a characteristic of gd TCRs compared to ab TCRs?

<p>They are often broadly cross-reactive. (A)</p> Signup and view all the answers

Which types of molecules do some gd T cell subsets specifically respond to in terms of stress?

<p>Stress-related molecules expressed by sick host cells (A)</p> Signup and view all the answers

How do the activation processes of gd T cells in peripheral tissues typically differ from those in epidermal and intestinal tissues?

<p>Epidermal and intestinal gd T cells depend on stress ligand engagement for costimulation. (A)</p> Signup and view all the answers

What role do antigen-presenting cells (APCs) play in the activation of gd T cells during inflammation?

<p>They supply stimulatory cytokines and promote activation. (C)</p> Signup and view all the answers

What is a shared characteristic between some gd T cells and natural killer (NK) cells regarding regulation?

<p>Some gd T cells express NK inhibitory receptors recognizing MHC class I. (A)</p> Signup and view all the answers

Which of the following types of molecules are NOT known to be recognized by gd T cells?

<p>High molecular weight carbohydrates (C)</p> Signup and view all the answers

Which statement best describes the specificity of certain gd T cell subsets?

<p>They can counter a specific group of pathogens based on V segment usage. (C)</p> Signup and view all the answers

What cytokine does activated gd T cells induce epithelial cells to produce?

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

Which growth factor is secreted by activated gd T cells to aid in wound healing?

<p>Keratinocyte Growth Factor (A)</p> Signup and view all the answers

What differentiates gd T cells from ab T cells in their development origin?

<p>gd T cells emerge from the same precursor as ab T cells and NK cells. (A)</p> Signup and view all the answers

Which statement accurately describes the relationship between gd T cells and immunological memory?

<p>gd T cells do not possess features of immunological memory. (D)</p> Signup and view all the answers

What is a known influence of cytokines produced by gd T cell effectors on other immune cells?

<p>They promote the differentiation of ab T cells into Th1, Th2, or Th17 effectors. (B)</p> Signup and view all the answers

During what gestational period are gd TCRgd genes detected in thymocytes of humans?

<p>By week 8 (A)</p> Signup and view all the answers

Which type of signaling pathway differs between gd T cells and ab T cells upon TCR stimulation?

<p>The pathways linking TCR stimulation to cytokine production (B)</p> Signup and view all the answers

Which type of TCRs are predominantly found on intestinal gd T cells?

<p>Vg1Vd2 TCRs (D)</p> Signup and view all the answers

What is a key difference between gd TCRs and ab TCRs in terms of antigen recognition?

<p>gd TCRs can bind directly to non-peptide antigens without presentation. (B)</p> Signup and view all the answers

Which of the following molecules are recognized by some gd T cell subsets specific to stress?

<p>Heat shock proteins (B)</p> Signup and view all the answers

How do gd T cells differ in their activation in peripheral tissues compared to epidermal and intestinal tissues?

<p>Epidermal and intestinal gd T cells are costimulated primarily through stress ligands. (C)</p> Signup and view all the answers

Which role do antigen-presenting cells (APCs) play in the activation of gd T cells during inflammation?

<p>APCs provide stimulatory cytokines or unknown intercellular contacts. (B)</p> Signup and view all the answers

Which of the following molecules are NOT typically recognized by gd T cells?

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

What characteristic of gd T cell subsets defined by V segment usage allows them to target specific types of pathogens?

<p>Competence to respond to stress-related antigens. (A)</p> Signup and view all the answers

What mechanism do some gd T cells use for activation that differs from conventional ab T cell activation?

<p>They can be activated with phosphorylated metabolites without additional costimulation. (A)</p> Signup and view all the answers

Which statement correctly describes a major function of gd T cells in host defense?

<p>They can respond to a broad range of antigens without MHC involvement. (B)</p> Signup and view all the answers

What anatomical location is NOT commonly associated with high concentrations of gd T cells?

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

Which of the following accurately describes the nature of gd T cell TCRs?

<p>They can recognize both soluble and cell-bound ligands. (B)</p> Signup and view all the answers

What is a characteristic response of gd T cells upon activation compared to ab T cells?

<p>They often respond in smaller numbers and more rapidly. (C)</p> Signup and view all the answers

Which broad category of antigens can gd T cells recognize that is usually not addressed by ab T cells?

<p>Non-protein antigens such as lipids and phosphorylated nucleotides. (C)</p> Signup and view all the answers

Flashcards

NKT cells' rapid response

NKT cells react quickly, acting as a primary defense against bacterial and viral infections.

NKT cell Ag recognition

NKT cells recognize glycolipids and glycosphingolipids presented on CD1d molecules by antigen-presenting cells.

Invariant NKT cells

NKT cells with a unique TCR; the alpha chain is mostly unchanging, while the beta chain shows some variation.

NKT cell activation

NKT cell activation can be direct, through activation by certain pathogen-derived glycolipid Ags, or indirect, from microbes lacking these glycolipid antigens.

Signup and view all the flashcards

NKT cell effector function

Activated NKT cells primarily secrete cytokines and chemokines, playing a key role in innate immunity.

Signup and view all the flashcards

gd T cell effector functions

gd T cells, activated by antigens, produce cytokines that activate NK cells and macrophages, support the differentiation of other T cells, and affect antibody production by B cells.

Signup and view all the flashcards

gd T cell cytokine secretion

Activated gd T cells release molecules that direct leukocyte movement and tissue repair.

Signup and view all the flashcards

gd T cell wound healing

gd T cells can prompt skin cells to produce molecules that aid in wound closure.

Signup and view all the flashcards

gd T cell vs. ab T cell memory

Unlike ab T cells, gd T cells do not exhibit immunological memory.

Signup and view all the flashcards

gd T cell antigen presentation

gd T cells can act as antigen-presenting cells to ab T cells.

Signup and view all the flashcards

gd T cell development timing

gd T cells are among the first T cells produced during fetal development.

Signup and view all the flashcards

NKT cell characteristics

NKT cells have similarities to both cytotoxic T cells and natural killer cells.

Signup and view all the flashcards

NKT cell location

NKT cells are found throughout the body, where other T and NK cells reside.

Signup and view all the flashcards

NKT cell activation speed

NKT cells can quickly release cytokines after activation, without needing to mature into effector cells.

Signup and view all the flashcards

NKT cell cytokine role

Activated NKT cells primarily secrete cytokines and chemokines that play a key role in innate immunity.

Signup and view all the flashcards

gd T cells role

gd T cells are a type of T cell that plays a role in innate immunity, responding to antigens from pathogens or stressed cells. Unlike T cells with other types of receptors, gd T cells can quickly respond, and are often the first line of defense.

Signup and view all the flashcards

gd T cell antigens

gd T cells recognize a wider variety of antigens than other T cells. These can include intact proteins, peptides, lipids, and other molecules from pathogens or stressed cells.

Signup and view all the flashcards

gd T cell location in the body

gd T cells are primarily found in the skin and mucosal tissues, rather than in secondary lymphoid organs like other T cells.

Signup and view all the flashcards

gd T cell vs. ab T cell response

gd T cells respond more quickly than other T cells. They often act quickly in response to threats, even without prior activation signals (costimulation).

Signup and view all the flashcards

gd T cells and immune memory

Unlike other T cells (like ab T-cells), gd T cells do not provide lasting immunity (memory).

Signup and view all the flashcards

gd T cell effector functions

Activated gd T cells produce cytokines that help activate other immune cells (like NK cells and macrophages), support the development of other T cells, and influence antibody production.

Signup and view all the flashcards

NKT cell characteristics

NKT cells share traits of both cytotoxic T cells and natural killer cells.

Signup and view all the flashcards

NKT Cell Activation Speed

NKT cells can release cytokines quickly after activation without needing to develop into effector cells.

Signup and view all the flashcards

gd T cell development timing

gd T cells are some of the first T cells produced during fetal development.

Signup and view all the flashcards

gd T cell location

gd T cells are often found in the skin and mucosal tissues, unlike other T cells that are more common in lymph nodes and spleen.

Signup and view all the flashcards

gd T cell vs. ab T-cell memory

gd T cells don't develop immunological memory like conventional T cells, while ab T cells produce memory cells.

Signup and view all the flashcards

NKT cell location

NKT cells are found throughout the body, including tissues like peripheral blood, the spleen, liver and lymph nodes.

Signup and view all the flashcards

gd T cell antigen recognition

gd T cells can directly bind non-peptide antigens, or antigens presented by non-classical MHC class Ib molecules or CD1 molecules.

Signup and view all the flashcards

gd T cell antigen types

gd T cells react to a broad range of substances, including peptides, proteins, pyrophosphates, phospholipids, lipoproteins, phosphorylated oligonucleotides, and alkyl amines.

Signup and view all the flashcards

gd T cell subset specificity

Specific gd T cell subsets are targeted against particular pathogen types or stress molecules released from damaged/infected/transformed host cells, like heat shock proteins.

Signup and view all the flashcards

gd T cell activation

Activation mechanisms of some gd T cells resemble those of NK cells more than ab T cells, as some gd T cells express NK inhibitory receptors, and can be activated without traditional costimulation.

Signup and view all the flashcards

gd T cell location

gd T cells commonly reside in peripheral tissues like the skin and intestines, often in areas of inflammation.

Signup and view all the flashcards

gd T cell activation costimulation

Peripheral gd T cell activation may involve conventional CD28-mediated costimulatory signals, whereas gd T cells in the skin and intestines are triggered by co-stimulation from other surface receptors.

Signup and view all the flashcards

gd T cells and memory

gd T cells, unlike ab T cells, generally do not exhibit immunological memory.

Signup and view all the flashcards

gd T cell in immune response

gd T cells are part of the faster initial immune response to various threats, responding to stressed/infected cells or pathogens, and helping activate other immune cells via cytokine signaling; hence gd T cells are an adaptive immunity part.

Signup and view all the flashcards

gd T cell location

gd T cells are primarily found in the skin and mucosal tissues, unlike other T cells, which are more common in secondary lymphoid organs.

Signup and view all the flashcards

gd T cell antigen recognition

gd T cells recognize a broader range of antigens, including intact proteins, peptides, lipids, and other molecules from pathogens or stressed cells.

Signup and view all the flashcards

gd T cell response vs. ab T cells

gd T cells respond faster than ab T cells. They can act quickly to threats, even without the traditional activation signals (costimulation).

Signup and view all the flashcards

gd T cell memory

Unlike ab T cells, gd T cells do not develop immunological memory.

Signup and view all the flashcards

gd T cell effector function

Activated gd T cells release cytokines to activate other immune cells (NK cells & macrophages), help other T cell development, and influence antibody production.

Signup and view all the flashcards

gd T cell effector functions

Activated gd T cells produce cytokines that activate NK cells and macrophages, support other T cell differentiation, and influence B cell antibody production.

Signup and view all the flashcards

gd T cell development timing

gd T cells are among the first T cells produced during fetal development, appearing before the fully developed adaptive immunity from ab T cells.

Signup and view all the flashcards

NKT cell characteristics

NKT cells have similarities to both cytotoxic T cells and natural killer cells.

Signup and view all the flashcards

NKT cell activation speed

NKT cells can release cytokines quickly after activation without needing to develop into effector cells.

Signup and view all the flashcards

NKT cell cytokine role

Activated NKT cells primarily secrete cytokines and chemokines, playing a crucial role in innate immunity.

Signup and view all the flashcards

gd T cell location

gd T cells are often found in peripheral tissues like skin and mucosal surfaces, unlike other T cells.

Signup and view all the flashcards

gd T cell vs. ab T cell memory

gd T cells, unlike ab T cells, do not exhibit immunological memory.

Signup and view all the flashcards

gd T cell location

gd T cells are frequently found in skin and mucosal tissues, unlike other T cells that are more common in lymph nodes and spleen.

Signup and view all the flashcards

gd T cell antigen recognition

gd T cells can directly recognize non-peptide antigens, or antigens presented by non-classical MHC class Ib molecules or CD1 molecules.

Signup and view all the flashcards

gd T cell antigen types

gd T cells respond to a wide array of molecules, including peptides, proteins, pyrophosphates, phospholipids, lipoproteins, phosphorylated oligonucleotides, and alkyl amines.

Signup and view all the flashcards

gd T cell subset specificity

Different subsets of gd T cells are tailored to target specific types of pathogens or stress molecules released from damaged/infected/transformed host cells, like heat-shock proteins.

Signup and view all the flashcards

gd T cell activation

Activation mechanisms of some gd T cells are more similar to natural killer cells (NK cells) than other ab T cells, with pathways potentially involving NK inhibitory receptors and skipping some traditional costimulation.

Signup and view all the flashcards

gd T cell activation costimulation

Peripheral gd T cells might be activated by typical CD28 co-stimulation, whereas gd T cells in the skin and intestines are triggered by other surface receptor engagements with stress ligands.

Signup and view all the flashcards

gd T cell vs. ab T-cell memory

Unlike ab T cells, gd T cells typically do not exhibit immunological memory.

Signup and view all the flashcards

gd T cell in immune response

gd T cells contribute to the initial immune response by reacting swiftly to stressed/infected cells or pathogens, and support other immune cells via cytokines; hence gd T cells play a part in adaptive immunity.

Signup and view all the flashcards

Study Notes

γδ T Cells: Overview

  • γδ T cells are a minority in humans and mice but a majority in ruminants (cows, sheep, pigs).
  • They express TCRs composed of TCRγ and TCRδ chains plus the CD3 complex.
  • They have either homodimeric CD8αα coreceptors or no coreceptor; thus, they are referred to as double-negative peripheral T cells.

γδ T Cells: Overview

  • γδ TCRs interact with ligands similarly as pattern recognition receptors (PRRs).
  • They can respond to antigens from various pathogens or stressed host cells.
  • Direct recognition means they do not require MHC or peptide Ag processing by APCs.
  • Intact proteins, peptides, lipids, and phosphorylated nucleotides can all be TCRγδ ligands. They can be soluble or bound to a cell surface.
  • Some stress molecules are recognized by γδ T cells but not by other cells like macrophages or neutrophils, filling a role in host defense.
  • γδ T cells proliferate and differentiate into γδ Th (helper) and γδ CTL (cytotoxic-like) effectors, like αβ T cells.
  • Activation is usually faster, with smaller numbers and often occurs without typical costimulation.

γδ Τ Cells: Anatomical Distribution

  • The distribution is different from αβ T cells.
  • They are found in small numbers in secondary lymphoid tissues and the thymus.
  • They are interspersed with epithelial cells in the skin (SALT) and mucosal tissues (MALT).
  • This means they are at the forefront of initial contact with pathogens or injurious substances.
  • Unlike αβ T cells, γδ T cells are often resident in a particular tissue type. They show a "canonical" TCR containing specific V gene segments.

γδ T Cells: Ag Recognition and Activation

  • γδ TCRs can directly bind to low-molecular-weight non-peptide antigens.
  • Some non-peptide antigens may be presented by non-classical MHC class Ib molecules (or CD1).
  • γδ TCRs are generally less specific than αβ TCRs and can broadly cross-react with various antigens.

γδ T Cells: Ag Recognition and Activation

  • γδ T cells respond to various bacterial, protozoan, and viral molecules, like peptides, proteins, pyrophosphates, phospholipids, lipoproteins, phosphorylated oligonucleotides, alkyl amines.
  • Specific subsets can recognize or target particular pathogen determinants.
  • γδ T cells can recognize stress molecules that are only prevalent in cells experiencing injury, infection, or cancerous transformation.
  • This broad recognition capability allows γδ T cells to respond to a wide range of threats.
  • Some stress molecules are small pyrophosphate-like molecules while others are peptides or whole proteins released from necrotic cells.

γδ T Cells: Ag Recognition and Activation

  • γδ T cell activation may resemble NK cell activation as some γδ cells express NK cell inhibitory receptors (for MHC class I).
  • Certain γδ T cells can be activated by phosphorylated metabolites, independent of CD28 or CD40 costimulation.
  • In peripheral tissues, γδ T cells tend to use conventional CD28 costimulation. In the skin and intestines, costimulation may involve other receptors engaged by stress ligands.
  • APCs can help activate cells in inflamed tissue by providing cytokines or unknown intercellular signals.

γδ T Cells: Effector Functions

  • γδ T cell effectors are similar to αβ T cell effectors, although the signaling pathways differ.
  • γδ T cells, following activation, release cytokines that can activate NK cells and macrophages, cause the differentiation of αβ T helper cells (Th1, Th2, or Th17), and affect isotype switching in B cells.
  • They produce molecules that affect leukocyte trafficking and wound healing.
  • Some activated γδ T cells can cause neighboring epithelial cells to produce nitric oxide (an antimicrobial).
  • Activated γδ T cells produce keratinocyte growth factor (KGF) to stimulate skin repair.
  • Immunological memory is not a feature of γδ T cells.
  • Recent studies suggest γδ T cells can act as antigen-presenting cells (APCs) for αβ T cells.

NKT Cells: Overview

  • NKT cells are T lineage cells with morphology and function characteristics similar to CTLs and NK cells.
  • They are found in low numbers throughout various tissues including the peripheral blood, spleen, liver, thymus, bone marrow, and lymph nodes.
  • Immediately upon activation, they secrete cytokines.
  • Their rapid response makes them important as a first line of defense against viral and bacterial infections.
  • Their produced cytokines affect the differentiation and function of αβ T cells.

NKT Cells: Ag Recognition and Activation

  • NKT cells recognize glycolipids, glycosphingolipids, and lipids presented by non-polymorphic CD1d molecules on professional and non-professional APCs.
  • NKT cells have a "semi-invariant" TCRαβ in which the TCRα chain is generally invariant; the TCRβ chain shows diversity.

NKT Cells: Ag Recognition and Activation

  • Several pathogens and host-derived glycolipids function as NKT cell antigens.
  • Activation of NKT cells recognizing CD1d-restricted glycolipids is direct, requiring no costimulation and cytokine receptor engagement.
  • Microbes lacking those lipids can still activate NKT cells through indirect pathways.
  • Sometimes TCR engagement alone is insufficient; IL-12/IL-18 or IFNα/β receptor engagement may be necessary.

NKT Cells: Activation (Figures)

  • Visual representations of activation, using panels of diagrams and arrows, displaying activation based on pathogen glycolipid, host glycolipid interactions, etc.

NKT Cells: Effector Functions

  • The characteristics of activated NKT cells align with innate-immunity cells.
  • NKT cells carry out effector functions immediately without differentiation and their main function is cytokine and chemokine secretion.

NKT Cells: Development

  • NKT cells are part of the adaptive immune system but share characteristics with innate cells.
  • They develop from the same NK/T precursors that produce αβ and γδ T cells.
  • Their development follows the αβ T cell pathway but diverges at the double positive (DP) stage.
  • IL-15 triggers continued maturation once they are positively selected from thymus non-hematopoietic cells.

Next Lecture

  • The next chapter is about mucosal and cutaneous immunity.

Studying That Suits You

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

Quiz Team

Related Documents

Lecture 26: gd T and NKT Cells - Immunology PDF

Description

This quiz explores the unique characteristics and functions of γδ T cells in humans, mice, and ruminants. It covers their T-cell receptor composition, their ability to recognize antigens without MHC, and their role in host defense. Test your knowledge on this important component of the immune system.

Use Quizgecko on...
Browser
Open
Browser
Browser