Podcast
Questions and Answers
What is the primary cytokine produced by Th1 cells that activates macrophages?
What is the primary cytokine produced by Th1 cells that activates macrophages?
Which cytokine is most prominently produced by Th2 cells in response to helminthic infections?
Which cytokine is most prominently produced by Th2 cells in response to helminthic infections?
What is the correct sequence in the polarization process of CD4+ T cell subsets?
What is the correct sequence in the polarization process of CD4+ T cell subsets?
Which CD4+ T cell subset primarily mediates phagocyte-independent defense?
Which CD4+ T cell subset primarily mediates phagocyte-independent defense?
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What is a key characteristic of Th17 cells?
What is a key characteristic of Th17 cells?
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What is the primary role of cytokines in CD4+ T cell responses?
What is the primary role of cytokines in CD4+ T cell responses?
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Which cytokines primarily stimulate the differentiation of Th1 cells?
Which cytokines primarily stimulate the differentiation of Th1 cells?
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Which function is primarily associated with Th1 cells?
Which function is primarily associated with Th1 cells?
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What factor is essential for the polarization of naive CD4+ T lymphocytes into Th1 cells?
What factor is essential for the polarization of naive CD4+ T lymphocytes into Th1 cells?
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What distinguishes the Th17 subset from other CD4+ T cell subsets?
What distinguishes the Th17 subset from other CD4+ T cell subsets?
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Which statement accurately describes the role of IFN-γ in CD4+ T cell responses?
Which statement accurately describes the role of IFN-γ in CD4+ T cell responses?
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What are the primary cytokines that contribute to the differentiation of TH1 cells?
What are the primary cytokines that contribute to the differentiation of TH1 cells?
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Which of the following statements about Th1 cells is incorrect?
Which of the following statements about Th1 cells is incorrect?
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Which statement best describes the relationship between Th1 cells and antigen presentation?
Which statement best describes the relationship between Th1 cells and antigen presentation?
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What is a characteristic feature of the therapeutic applications of IFN-γ in veterinary medicine?
What is a characteristic feature of the therapeutic applications of IFN-γ in veterinary medicine?
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Where does the initial activation of CD4+ T cells occur?
Where does the initial activation of CD4+ T cells occur?
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Which of the following are generated from CD4+ T cell activation?
Which of the following are generated from CD4+ T cell activation?
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What is the primary function of effector CD4+ T cells
What is the primary function of effector CD4+ T cells
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The three major subsets of CD4+ effector T cells include all of the following except
The three major subsets of CD4+ effector T cells include all of the following except
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What is the term used to describe the development process of Th1, Th2, Th17 cells from naive CD4+ T lymphocytes
What is the term used to describe the development process of Th1, Th2, Th17 cells from naive CD4+ T lymphocytes
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Which subset of CD4+ T cells is most involved in phagocyte-mediated host defense?
Which subset of CD4+ T cells is most involved in phagocyte-mediated host defense?
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The Th1 subset is primarily induced by which of the following?
The Th1 subset is primarily induced by which of the following?
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What cytokines are essential for Th1 differentiation?
What cytokines are essential for Th1 differentiation?
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Th1 differentiation is promoted by transcription factors such as
Th1 differentiation is promoted by transcription factors such as
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The principle function of Th1 cells is to
The principle function of Th1 cells is to
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Th1 cells or follicular helper T cells stimulate the production of which antibody class?
Th1 cells or follicular helper T cells stimulate the production of which antibody class?
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Effector functions of Th1 cells are mainly mediated by which cytokine?
Effector functions of Th1 cells are mainly mediated by which cytokine?
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Which of the following is NOT an effect of IFN gamma in the Th1 cell function?
Which of the following is NOT an effect of IFN gamma in the Th1 cell function?
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IFN gamma activates macrophages primarily to :
IFN gamma activates macrophages primarily to :
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IFN gamma promotes which subclass switching in B cells?
IFN gamma promotes which subclass switching in B cells?
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How does IFN gamma affect Th2 and Th17 cell development?
How does IFN gamma affect Th2 and Th17 cell development?
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The major Th1 cytokine, IFN gamma is also known as
The major Th1 cytokine, IFN gamma is also known as
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The therapeutic use of IFN-γ in veterinary medicine includes all the following, except:
The therapeutic use of IFN-γ in veterinary medicine includes all the following, except:
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The Th2 subset: What two cells play a central role in its defense?
The Th2 subset: What two cells play a central role in its defense?
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Th2 subset: It’s important for the eradication of _____ infections
Th2 subset: It’s important for the eradication of _____ infections
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Th2 cells stimulate _______ , ______ and ______
Th2 cells stimulate _______ , ______ and ______
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Th17 cells are critical for defense against which type of pathogens?
Th17 cells are critical for defense against which type of pathogens?
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Which cytokines are essential for the differentiation of TH17 cells?
Which cytokines are essential for the differentiation of TH17 cells?
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What role does IL-17 play in the immune response mediated by TH17 cells?
What role does IL-17 play in the immune response mediated by TH17 cells?
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Which statement about the maintenance of TH17 cells is correct?
Which statement about the maintenance of TH17 cells is correct?
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Which best describes the contribution of TH17 cells to inflammatory diseases?
Which best describes the contribution of TH17 cells to inflammatory diseases?
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Th17 cells help combat infections by recruiting which type of immune cells to the infection site?
Th17 cells help combat infections by recruiting which type of immune cells to the infection site?
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Which of the following cytokines is NOT involved in Th17 differentiation or function?
Which of the following cytokines is NOT involved in Th17 differentiation or function?
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Study Notes
CD4+ T Cell Differentiation
- CD4+ T cells differentiate into effector and memory cells following activation.
- Effector functions of CD4+ T cells primarily involve cytokine secretion.
Effector and Memory Cell Generation
- CD4+ T cell activation occurs in lymphoid organs.
- Effector and memory cells are generated in response to activation.
- Effector cells migrate to the site of infection.
- Effector cells indirectly kill infectious agents.
CD4+ T Cell Subsets
- CD4+ T cells are classified based on the cytokines they produce.
- Development of subsets involves induction, stable commitment, and clonal expansion stages.
Tн1 Cells
- Induced by microbes that activate phagocytes.
- Major effector T cell population involved in cell-mediated immunity.
- Differentiate in the presence of IL-2 and IFN-γ produced by dendritic cells, macrophages, and NK cells.
Tн2 Cells
- Mediate phagocyte-independent defense.
- Eosinophils and mast cells play a central role in defense.
- Important in helminthic infections and allergic disease.
- Development is stimulated by IL-4 in response to helminths and allergens.
Tн17 Cells
- To be added.
Cytokine Production by CD4+ T Cells
- Tн1: IFN-γ
- Tн2: IL-4, IL-5, IL-13
- Tн17: IL-17A, IL-17F, IL-22
Roles of CD4+ T Cell Subsets
-
Tн1:
- Activate macrophages in the classical pathway.
- Stimulate production of IgG antibodies.
- Effector functions are mediated by IFN-γ.
- Promotes IgG2a switching while inhibiting IgE switching.
- Inhibits development of Tн2 and Tн17 cells.
- Increases MHC I and II expression on antigen-presenting cells (APCs).
-
Tн2: To be added
-
Tн17: To be added
CD4+ T Cell Responses
- CD4+ T cell responses involve initial activation in lymphoid organs, the generation of effector and memory cells, the migration of effector cells to sites of infection, and the elimination of infectious pathogens at these sites.
- CD4+ T cell functions are mainly mediated by cytokines.
- CD4+ effector T cells are classified according to the cytokines they produce.
- The three major subsets of CD4+ effector T cells are: Th1, Th2, Th17, and follicular helper T cells.
- Th1, Th2, and Th17 cells develop from naive CD4+ T lymphocytes.
- The development process of these subsets is referred to as polarization of T cells.
- The Th1 subset is induced by microbes that are ingested by phagocytes and activate phagocytes.
- Th1 cells are the major effector T cell population in phagocyte-mediated host defense and a central reaction of cell-mediated immunity.
- Th1 cells differentiate in the presence of IL-12 and IFN-γ produced by dendritic cells, macrophages, and NK cells.
- IFN-γ and IL-12 stimulate Th1 differentiation by activating the transcription factors T-bet, STAT1, and STAT4.
- The principal function of Th1 cells is to activate macrophages to ingest and destroy microbes.
- Th1 or follicular helper T cells stimulate the production of some IgG antibodies.
- Effector functions of Th1 cells are mediated through IFN-γ.
CD4+ T Cell Responses
- CD4+ T cell responses involve initial activation in lymphoid organs, generating effector and memory cells that migrate to infection sites.
- These cells eliminate pathogens via cytokine-mediated functions.
CD4+ T Cell Subsets
- Three major subsets of CD4+ effector T cells: Th1, Th2, Th17, and follicular helper T cells
- All develop from naive CD4+ T lymphocytes, a process known as T cell polarization.
TH1 Subset
- Induced by microbes ingested or activating phagocytes.
- TH1 is the major effector T cell in phagocyte-mediated host defense, central to cell-mediated immunity.
- Differentiates in the presence of IL-12 and IFN-γ, produced by dendritic cells, macrophages, and NK cells.
- IFN-γ and IL-12 stimulate differentiation by activating T-bet, STAT1, and STAT transcription factors.
TH1 Cell Functions
- Primarily activate macrophages to ingest and destroy microbes.
- Stimulate IgG antibody production (via follicular helper T cells).
- Effector functions mediated through IFN-γ.
Importance of IFN-γ for TH1 Cells
- Activates macrophages to kill phagocytosed microbes.
- Promotes IgG2a subclass switching in B cells and inhibits IgE switching.
- Amplifies the TH1 subset while inhibiting TH2 and TH17 development.
- Stimulates expression of MHC I and II, enhancing antigen presentation.
Therapeutic Applications of IFN-γ
- Recombinant canine IFN-γ (KT-100) for atopic dermatitis in veterinary medicine.
- Human IFN-γ (hIFN-γ) in clinical trials for canine astrocytoma (gene therapy).
- Feline IFN-γ (fIFN-γ) combined with fIL-2 and fGM-CSF for fibrosarcoma (clinical trials, gene therapy).
- IFN-γ gene therapy for canine brain tumors.
TH17 Cells
- TH17 cells are a subset of T helper cells critical for immune responses to extracellular bacteria and fungi.
- They are responsible for recruiting leukocytes, particularly neutrophils, to sites of infection and inducing inflammation.
- TH17 cell differentiation is initiated by pro-inflammatory cytokines such as IL-1 and IL-6.
- IL-23 plays a crucial role in maintaining the proliferation and differentiation of TH17 cells.
- TH17 cells produce IL-17, a key cytokine that triggers neutrophil-rich inflammation, which is essential for combating extracellular pathogens.
- IL-17 promotes the production of antimicrobial substances, further enhancing the immune response.
- While essential for protection against infection, TH17 cells can also contribute to the pathogenesis of inflammatory diseases.
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Description
Test your knowledge on CD4+ T cell differentiation and its various subsets. This quiz covers topics including effector and memory cell generation, as well as the roles of Tn1 and Tn2 cells in immune responses. Challenge yourself and see how much you know about the immune system!