Podcast
Questions and Answers
Which cytokine is primarily responsible for promoting class switching to IgG1 and IgE?
Which cytokine is primarily responsible for promoting class switching to IgG1 and IgE?
- IFN-g
- IL-4 (correct)
- IL-10
- IL-2
What is the main function of IFN-g in the immune response?
What is the main function of IFN-g in the immune response?
- Enhances T cell growth
- Increases MHC expression (correct)
- Promotes neutrophil activation
- Stimulates B cell differentiation
Which cytokine is known to inhibit Th1 responses and is produced by macrophages and Th2 cells?
Which cytokine is known to inhibit Th1 responses and is produced by macrophages and Th2 cells?
- TNF-a
- IL-6
- IL-10 (correct)
- IL-17
What key role does IL-17 play in the immune system?
What key role does IL-17 play in the immune system?
What strategic function do TNF alpha inhibitors serve in therapy?
What strategic function do TNF alpha inhibitors serve in therapy?
What is the primary method through which cytotoxic T lymphocytes (CTLs) induce apoptosis in infected cells?
What is the primary method through which cytotoxic T lymphocytes (CTLs) induce apoptosis in infected cells?
Which statement accurately describes the action of CTLs?
Which statement accurately describes the action of CTLs?
What role do Killer Inhibitory Receptors (KIRs) play in the activity of Natural Killer (NK) cells?
What role do Killer Inhibitory Receptors (KIRs) play in the activity of Natural Killer (NK) cells?
What is a consequence of necrosis compared to apoptosis?
What is a consequence of necrosis compared to apoptosis?
How do CTLs achieve specificity in targeting infected cells?
How do CTLs achieve specificity in targeting infected cells?
What determines whether NK cells will proceed to kill a target cell?
What determines whether NK cells will proceed to kill a target cell?
Which mechanism is NOT used by CTLs to kill infected cells?
Which mechanism is NOT used by CTLs to kill infected cells?
What is the primary consequence of CTL killing through apoptosis?
What is the primary consequence of CTL killing through apoptosis?
What is the primary role of cytokines in the immune response?
What is the primary role of cytokines in the immune response?
Which of the following describes a characteristic feature of cytokines concerning their effect?
Which of the following describes a characteristic feature of cytokines concerning their effect?
What happens when MHC class I is prevented from reaching the cell surface?
What happens when MHC class I is prevented from reaching the cell surface?
Which cytokine is known to activate infected macrophages in a delayed type hypersensitivity response?
Which cytokine is known to activate infected macrophages in a delayed type hypersensitivity response?
What type of immune cells do CD8+ cytotoxic T cells primarily target?
What type of immune cells do CD8+ cytotoxic T cells primarily target?
How do Th1 cells contribute to the immune response against intracellular pathogens?
How do Th1 cells contribute to the immune response against intracellular pathogens?
In what way do cytokines exhibit redundancy in their function?
In what way do cytokines exhibit redundancy in their function?
What is the fate of macrophages infected with Mycobacterium tuberculosis when unaffected by activated Th1 cells?
What is the fate of macrophages infected with Mycobacterium tuberculosis when unaffected by activated Th1 cells?
What is primarily responsible for killing infected cells during a cell mediated immune response?
What is primarily responsible for killing infected cells during a cell mediated immune response?
What role do natural killer cells play in the immune system?
What role do natural killer cells play in the immune system?
Which of the following cytokines is involved in promoting an antiviral response?
Which of the following cytokines is involved in promoting an antiviral response?
How does the immune system primarily respond to intracellular pathogens?
How does the immune system primarily respond to intracellular pathogens?
What is the role of CD4+ T cells in activating CD8+ T cells?
What is the role of CD4+ T cells in activating CD8+ T cells?
What property describes the ability of multiple cytokines to produce similar effects?
What property describes the ability of multiple cytokines to produce similar effects?
Which statement about MHC class I molecules is correct?
Which statement about MHC class I molecules is correct?
Which cytokine is primarily involved in promoting the differentiation of T helper cells?
Which cytokine is primarily involved in promoting the differentiation of T helper cells?
What is the primary role of TNF-alpha in the immune response?
What is the primary role of TNF-alpha in the immune response?
What is a significant consequence of inhibiting TNF-alpha?
What is a significant consequence of inhibiting TNF-alpha?
Which cytokine is primarily responsible for promoting antibody production and activating macrophages?
Which cytokine is primarily responsible for promoting antibody production and activating macrophages?
In response to an APC, what process allows TH cells to proliferate?
In response to an APC, what process allows TH cells to proliferate?
What primarily maintains the granuloma formed during a TB infection?
What primarily maintains the granuloma formed during a TB infection?
Which of the following is a major characteristic of a super-killing macrophage?
Which of the following is a major characteristic of a super-killing macrophage?
What role do cytokines play in TH cell differentiation?
What role do cytokines play in TH cell differentiation?
What is a potential outcome if the functions of TNF-alpha remain intact?
What is a potential outcome if the functions of TNF-alpha remain intact?
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Study Notes
Cell Mediated Immunity
- How the cell-mediated immune response gets activated and responds to intracellular pathogens:
- CD8+ T cells (cytotoxic T cells) are activated by MHC Class I presenting viral peptides.
- CD4+ T cells help activate CD8+ T cells, which then differentiate into cytotoxic T cells (CTLs).
- CTLs recognize infected cells by MHC Class I and directly kill the cells (without causing inflammation) via apoptosis.
- CTLs kill through perforin/granzyme, Fas/Fas-ligand, TNF-beta (lymphotoxin).
Natural Killer Cells
- Role of Natural Killer cells:
- They kill cells that lack MHC Class I expression (e.g., virus-infected cells, tumor cells).
- They can also be activated by antibodies bound to the surface of target cells.
- They have killer activating receptors (KARs) and killer inhibitory receptors (KIRs) on their surface.
- KIRs prevent NK cells from attacking normal cells by recognizing MHC Class I molecules.
Cytokines
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What are cytokines?
- Small proteins that stimulate immune cells to proliferate and differentiate.
- Many are called interleukins (IL-1,IL-2), but there are other important ones like interferon gamma (IFN-g) and tumor necrosis factor alpha (TNF-a).
-
General properties of cytokines:
- Pleiotropy: A single cytokine can act on different cells, causing different effects.
- Redundancy: Multiple cytokines can exert the same effect.
- Synergy: Combined cytokines can produce greater effects than alone
- Antagonism: Some cytokines can block the effects of other cytokines.
Cytokine Short List
- IL-2: T cell growth factor; enhances CTLs and NK cells.
- IL-4: Key Th2 cytokine; promotes antibody production, class switching to IgG1 and IgE, differentiation of B cells.
- IFN-g: Key Th1 cytokine; promotes MHC expression, blocks IgE production, inhibits Th2 proliferation, activates macrophages in delayed-type hypersensitivity (DTH) response.
- IL-10: Key Th2 cytokine; inhibits Th1 responses, produced by Th2 cells and macrophages.
- IL-17: Key Th17 cytokine; recruits and activates neutrophils.
- TNF-a: Involved in inflammation, DTH response, granuloma formation.
Delayed-Type Hypersensitivity (DTH) Response
- How it works:
- Macrophages ingest intracellular pathogens, like Mycobacterium tuberculosis.
- Some pathogens evade phagocytosis and live inside macrophages.
- IFN-g helps activate macrophages to kill the pathogen.
- TNF-a also plays a role in DTH and formation of granulomas, which wall off infected areas.
Cytokine Inhibition in Treatment
- TNF-alpha Inhibitors: Used for Crohn's disease and rheumatoid arthritis.
- IL-17 Inhibitors: Used for psoriasis.
- IL-6 Inhibitors: Used for severe COVID-19, hyperinflammatory states.
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