64 Questions
What makes conventional DCs the most efficient APCs for initiating primary T cell responses?
Expressing high levels of peptide-MHC complexes, costimulators, and cytokines
Which cells are strategically located at sites of entry of microbes and in tissues that may be colonized by microbes?
Dendritic cells (DCs)
What allows specialized DCs (cDC1) to efficiently cross-present antigens to CD8+ T cells?
Transferring internalized proteins from phagosomes into the cytosol
What is one key property that differentiates mature DCs from other antigen-presenting cells?
Expressing high levels of peptide-MHC complexes
What is the primary function of dendritic cells (DCs) in relation to T cell responses?
Initiating primary T cell responses
Which DC subset is especially efficient at cross-presentation, presenting ingested antigens on class I MHC molecules to CD8+ T cells?
Type 1 cDCs (cDC1)
Which DC subset is the major source of type I IFN and plays an essential role in innate immune responses to viruses?
Plasmacytoid DCs (pDC)
Which DC subset presents captured antigens to CD4+ T cells and is crucial for initiating responses of these T cells?
Type 2 cDCs (cDC2)
Which DC subset can be induced to develop from monocytes under inflammatory conditions but has unclear roles in immune responses?
Monocyte-derived DCs (moDC)
Which type of DC captures antigens and transports them to secondary lymphoid organs, being involved in antigen presentation to naive CD4+ and CD8+ T cells?
Conventional DCs
Which cells, located in the epidermis, were among the earliest identified dendritic cells?
Langerhans cells
Which cells are most effective at capturing and transporting antigens for presentation to naive T cells?
Dendritic cells
What enhances the antigen-presenting function of APCs?
Exposure to microbial products
Which cells are more important for the activation of naive T cells?
Antigen-presenting cells
Where are microbes and protein antigens that enter through epithelia concentrated?
Lymph nodes
Which organ captures blood-borne antigens mostly?
Spleen
What is the main function of MHC molecules in antigen processing?
To bind and display antigens for recognition by T cells
Why do T lymphocytes recognize cell-associated antigens and not soluble, cell-free antigens?
Because MHC class I and II molecules only present cell-associated antigens
Which cell type is the most effective antigen-presenting cell (APC) for activating naive T cells?
Dendritic cells (DCs)
Why is it essential for antigen-presenting cells (APCs) to carry antigens to secondary lymphoid organs?
To concentrate antigens where naive T cells circulate
What is the primary source of foreign protein antigens that induce T cell-mediated immune responses?
Intact folded proteins
Why do most T lymphocytes recognize only short peptides?
Due to the structure of MHC molecules
Which immune responses are usually induced by nonprotein antigens?
Humoral immune responses are induced by nonprotein antigens.
What are the additional stimuli provided by APCs to fully activate T cells?
Costimulators are provided by APCs to fully activate T cells.
Which type of lymphocytes recognize peptide antigens displayed by MHC molecules?
CD4+ and CD8+ T cells recognize peptide antigens displayed by MHC molecules.
What process allows DCs to initiate CD8+ T cell responses to the antigens of ingested cells?
Cross-presentation
Which pathway involves the proteolytic cleavage of proteins by enzymes in lysosomes and late endosomes?
Class II MHC pathway
Which molecule is associated with newly synthesized class II MHC molecules and transported from the ER to endosomal vesicles?
Invariant chain (Ii)
What type of proteins generates peptides bound to class II MHC molecules for recognition by CD4+ helper T cells?
Proteins synthesized by extracellular microbes
What are the effector mechanisms that eliminate extracellular antigens activated by?
CD4+ helper T cells
Which type of T cells functions to eliminate cells harboring intracellular infections?
CD8+ CTLs
What is the process called when DCs present antigens from virus-infected or tumor cells and prime T cells specific for these antigens?
Cross-presentation
Where are peptides generated by proteasomes in the cytosol translocated for binding to newly synthesized class I MHC molecules?
Endoplasmic reticulum
What is the specialized transporter protein called that mediates the translocation of peptides ranging from 8 to 16 amino acids from the cytosol into the endoplasmic reticulum?
TAP
Which type of proteasomes are specifically found in immune cells like dendritic cells and other antigen-presenting cells?
Immunoproteasomes
Which protein assists in loading peptides onto newly synthesized class I MHC molecules in the endoplasmic reticulum?
Tapasin
Why do peptides preferentially bind to class I rather than class II MHC molecules after being transported into the ER?
Peptides' affinity for class I MHC
What stabilizes the Class II MHC molecules on the surface of antigen-presenting cells (APCs)?
Peptide antigens
Which type of T cells are activated by helper T lymphocytes to eliminate extracellular antigens?
B lymphocytes
What type of antigens are presented to CD8+ cytotoxic T lymphocytes?
Cytosolic antigens
What is the essential role of the CD4 coreceptor in the antigen presentation process?
Recognition of nonpolymorphic regions on class II MHC molecules
Which cell type recognizes only peptides displayed by major histocompatibility complex (MHC) molecules on APCs?
CD4+ T cells
Which immune response is induced by CD8+ cytotoxic T lymphocytes?
Killing of antigen-expressing cells
What enables mature DCs to efficiently activate T lymphocytes?
High levels of peptide-MHC complexes, costimulators, and cytokines
Which property makes specialized DCs (cDC1) efficient at cross-presenting antigens?
Transfer of internalized proteins from phagosomes into the cytosol
Which cells migrate from epithelia and tissues via lymphatics in response to chemokines?
Activated DCs
Which cells are strategically located at the common sites of entry of microbes and foreign antigens?
Dendritic cells
What is the role of chemokines in the immune response?
Promote DC migration from epithelia and tissues via lymphatics
Which type of cells can present peptides derived from cytosolic protein antigens to CD8+ CTLs?
All nucleated cells
Which type of antigens are degraded by proteasomes to yield peptides that are displayed on class I MHC molecules?
Proteins that are present in the cytosol
Which type of microbes produce antigens in the cytosol of cells?
Microbes that are present in the cytosol
Which type of cells can express class II MHC molecules and present antigens to T cells?
Only endothelial and some epithelial cells
Which type of cells are involved in the presentation of antigens of ingested microbes to effector T cells?
Macrophages
Which type of cells are involved in the internalization of protein antigens and the presentation of peptides derived from these proteins to helper T cells?
B lymphocytes
What is the function of MHC molecules in antigen processing?
To bind and display peptides for recognition by CD4+ and CD8+ T cells
Which cell type is the most effective antigen-presenting cell (APC) for activating naive T cells?
Dendritic cells
What are the additional stimuli provided by APCs to fully activate T cells?
Second signals or costimulators
What makes conventional DCs the most efficient APCs for initiating primary T cell responses?
Their high expression of costimulatory molecules
What is the main difference between CD4+ and CD8+ T cells in antigen processing?
CD4+ T cells recognize peptides bound to class II MHC molecules, while CD8+ T cells recognize peptides bound to class I MHC molecules
Which cell type is crucial for initiating responses of CD4+ T cells?
Dendritic cells
What type of T cells functions to eliminate cells harboring intracellular infections?
CD8+ cytotoxic T cells
Which DC subset is especially efficient at cross-presentation, presenting ingested antigens on class I MHC molecules to CD8+ T cells?
cDC1
Which DC subset can be induced to develop from monocytes under inflammatory conditions but has unclear roles in immune responses?
Monocyte-derived DCs
What enhances the antigen-presenting function of APCs?
High expression of costimulatory molecules
This quiz covers the process of antigen capture, concentration in secondary lymphoid organs, and activation of immune responses. Topics include the entry of antigens into the body through different surfaces and their colonization in tissues.
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