101 Questions
What is one of the mechanisms by which infected cells can be destroyed?
The infected cell undergoes rapid apoptosis, preventing invader growth
Which type of antigens are involved in the destruction of viruses located in the cell cytoplasm or nucleus?
Endogenous antigens
Which pathway for apoptosis involves the release of cytochrome c from mitochondria?
Intrinsic pathway
What cellular structure is responsible for the recruitment and activation of caspase 9 in the intrinsic pathway of apoptosis?
Apoptosome
After undergoing apoptosis, what happens to the lipid content of dying cells?
Lipid binds to macrophages and dendritic cells for phagocytosis
What effect does the presence of apoptotic cells have on T-cell stimulation?
Apoptotic cells suppress T-cell stimulation and induce tolerance
What type of cells die passively as a result of severe damage such as trauma or toxicity?
Necrotic cells
Which cells engulf necrotic cells during inflammation?
Dendritic cells
What is required to trigger the Tc response in cellular immune response?
Endogenous antigen presentation
Which molecules are involved in stimulating IL-12 and CCL22 production in dendritic cells?
Th1 cells
What do activated CD8+ Tc leave lymphoid organs to seek in cellular immune response?
Intracellular pathogens
How do activated CD8+ Tc kill their targets in the cellular immune response?
Perforin pathway
Which type of antigen is recognized by Tc cells on MHC Ia, not MHC II?
Endogenous antigens
What is the role of proteasomes in the cellular immune response?
Recycling peptide fragments
Which protein marks ubiquinated proteins for destruction in the cellular immune response?
Proteasome
What is the function of transporter proteins TAP in the cellular immune response?
Selecting peptides from the cytoplasm to endoplasmic reticulum lumen
How many MHC-peptide complexes can a cell express?
~106
Which receptor binds to MHC II and is associated with T helper cells?
CD4
What is the primary role of CD8 on a Tc cell during adhesion?
Enhancing the binding between Tc and its target
What percentage of human T cells are CD4+CD8-?
~65%
Which signaling molecules cluster at the center of the immunological synapse formed between a Tc cell and a target cell?
CD8
What is required for optimal activation of CD8+ T cells?
Binding of CD28 to CD86 on target cells
What happens to Tc granules' contents after they are secreted into the intracellular space of the synapse?
They aggregate polyperforins
Which molecules mediate the additional adhesion between a Tc cell and its target?
CD2-CD58 or CD48
During the cellular immune response, what is the final phase following 'lethal hit'?
Cell death
Which one of these receptors has high affinity for IgG?
CD64
Which T cell population is responsible for destroying endogenous antigens?
Effector or cytotoxic T cells
Which one of these molecules is not part of the immunoglobulin superfamily?
CD3
Which cytokine is predominantly produced by Th1 cells?
IFN-γ
Which one of these T cell populations is responsible for regulating immune responses?
T helper cells
Which one of these receptors is expressed only on Th cells and recognize MHC II?
CD4
Which one of these molecules is not a costimulator?
CD3
Which one of these molecules is not a cytokine?
CD40
Which one of these T cell populations promotes cell-mediated immune responses?
Th1 cells
Which one of these molecules is not a complement receptor?
CD64
Which type of cells are responsible for engulfing necrotic cells during inflammation?
Dendritic cells
What is the primary role of CD40 on dendritic cells during the cellular immune response?
Up-regulating MHC expression
Which signaling molecule is predominantly secreted by Th1 cells to activate dendritic cells?
IFN-γ
What happens to the lipid content of dying infected cells in the cellular immune response?
It is released into the extracellular space
What is the main function of IL-2 in the activation of CD8+ Tc cells?
Promoting cytokine synthesis by CD8+ Tc cells
In the cellular immune response, what directly causes the activation of CD8+ Tc cells when they encounter endogenous antigens?
MHC I on abnormal cells
What is the role of TNF-ß in cellular immune response?
Binds to TNF-ß death receptors on target cells to induce apoptosis
Which protein is responsible for trimerizing CD95L and CD95 to form DISC in Tc cells?
Granzyme B
What is the main function of FcγRI and FcγRII in cellular immune response?
Binding to target cells' antibodies
Which cytokine is predominantly produced by Th2 cells in rodents?
IL-5
What is the result of the binding of CD178 (CD95L) by CD95 (fas) in Tc or NK cells?
Formation of DISC with caspase 8 and 10
Which protein is responsible for directly killing target cells by activating sphingomyelinases leading to apoptosis?
Granulysin
What is the primary function of CD8 on a Tc cell during adhesion?
To enhance the binding between Tc and its target
What molecules mediate the additional adhesion between a Tc cell and its target?
CD2-CD58 or CD48
What is released into the intracellular space of the synapse after Tc granules are secreted?
Perforins and granzymes
What is the role of polyperforins in the cellular immune response?
To insert transmembrane channels into the target membrane
What is required for optimal activation of CD8+ T cells?
Signal from Ag-MHC-CD8 complexes and costimulatory signals
What happens to the lipid content of dying cells after undergoing apoptosis?
It is phagocytosed by macrophages
Which one of these microorganisms is not typically associated with survival and multiplication inside macrophages?
Escherichia coli
Which one of these cytokines is not primarily produced by Th1 cells during the cellular immune response?
Interleukin-4
Which one of these molecules is not involved in the activation of macrophages during the cellular immune response?
Insulin
Which one of these T cell populations is not involved in the destruction of infected cells during the cellular immune response?
Naive T cells
Which one of these cells is not responsible for engulfing necrotic cells during inflammation?
Erythrocytes
Which one of these receptors is expressed only on Th cells and recognize MHC II?
CD4
Which one of these molecules is not a costimulator?
CD64
Which one of these T cell populations is responsible for destroying endogenous antigens?
Effector or cytotoxic T cells
Which type of antigen is recognized by Tc cells on MHC Ia, not MHC II?
Endogenous antigens
What is the primary role of CD8 on a Tc cell during adhesion?
Binding to MHC Ia
Which one of these molecules is not part of the immunoglobulin superfamily?
CD118
What is one of the mechanisms by which infected cells can be destroyed?
Apoptosis
Which one of these receptors has high affinity for IgG?
CD64
What is required for optimal activation of CD8+ T cells?
TCR-peptide + MHC and costimulatory signals
Which cytokine is predominantly produced by Th1 cells?
IL-12
How does the cellular immune response contribute to the destruction of viruses located in the cell cytoplasm or nucleus?
By inducing membrane blebbing and caspase activation
Which molecule plays a crucial role in the extrinsic pathway of programmed cell death by binding to the CD95 death receptor?
Cytokines like TNF-ɑ
What is the main function of the apoptosome in the intrinsic pathway of programmed cell death?
Recruits and activates caspase 9
Which feature distinguishes the presentation of antigens from apoptotic cells compared to other infected cells by dendritic cells?
Expression of costimulatory molecules
What is the role of endonuclease activation in the process of programmed cell death?
Cleaves DNA during cellular immune response
Why are T cells not stimulated but turned off when dendritic cells present antigens from apoptotic cells?
Presence of costimulatory molecules
What is the main function of CD8 on a Tc cell during adhesion?
Enhancing the binding between Tc and its target
What additional adhesion molecules are involved in the interaction between a Tc cell and its target?
CD2-CD58
What occurs at the center of the immunological synapse between a Tc cell and a target cell?
Clustering of TCRs and signaling molecules
What is the primary role of perforins released by CD8+ Tc cells?
Inserting into the target cell membrane
What is the final phase of the cellular immune response following the 'lethal hit'?
Cell death
What is the mechanism through which Granzyme B triggers the release of mitochondrial cytochrome c in the target cell?
Perforin injection
Which molecules compose the polyperforins that are formed after P aggregation?
$12-18$ monomers
Which protein is involved in forming the DISC (Death-Inducing Signaling Complex) during the CD95 (Fas) pathway activation in Tc cells?
Caspase 10
Which cytotoxin, similar to CD95L, can bind to TNF-ß death receptors on target cells inducing apoptosis?
CD178 (Fas-ligand)
What is the main function of FcγRI and FcγRII in cellular immune response?
ADCC promotion
Which subset of CD4+ T helper cells is responsible for producing IL-2 and IFN-γ?
Th1
What is the antibacterial peptide produced by Tc and NK cells after activation, leading to target cell death through lipid membrane attack?
Granulysin
Which one of these cytokines is primarily involved in macrophage activation during the cellular immune response?
IFN-γ
Which one of these cells is responsible for destroying endogenous antigens in the cellular immune response?
Tc cells
Which one of these receptors is expressed only on Th cells and recognize MHC II?
CD4
Which one of these cytokines is not predominantly produced by Th1 cells during the cellular immune response?
IL-4
Which signaling molecule is predominantly secreted by Th1 cells to activate dendritic cells?
IFN-γ
Which receptor has a moderate affinity for IgG and only binds immune complexes?
CD32
Which type of lymphocytes are responsible for secreting immunoglobulins and destroying exogenous antigens?
B cells
Which major surface receptor of T cells binds to C3d and C3bi?
CD21
Which T cell antigen receptor (TCR) chains are associated with CD3?
α and β
Which costimulatory molecule is found on T-cells and binds to CD40 on APCs?
CD154
Which cytokine is produced by APCs and stimulates Th1 cells?
IL-12
Which T helper cell subpopulation promotes cell-mediated immune responses and produces IL-2 and IFN-γ?
Th1
Which type of cells are responsible for engulfing necrotic cells during inflammation?
Macrophages
Which type of antigens are recognized by Tc cells on MHC Ia, not MHC II?
Endogenous antigens
Which T cell population is responsible for destroying endogenous antigens?
Cytotoxic T cells
Test your knowledge on the cellular immune response focusing on antigen processing and presentation, as well as Tc cell activation in the context of virus-infected cells. Explore the different types of antigens and understand how they are recognized by specific immune cells.
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