Chapter 10: Antigen Presentation in Innate & Adaptive Immune Systems

What is the primary function of perforin and granzymes secreted by CD8+ T cells?

To induce apoptosis in target cells (correct)
To activate memory T cells
To enhance B cell receptor signaling
To facilitate antigen presentation by B cells

Which of the following is a key feature of memory T cells?

They can directly present antigen to other T cells via MHC class II molecules
They express both IgM and IgD B cell receptors
They require T cell help for activation and differentiation
They have a lower activation threshold and can respond more rapidly to the same antigen (correct)

What is the primary function of the B cell receptor (BCR) complex?

To bind and crosslink identical epitopes on the surface of an antigen (correct)
To activate memory B cells more rapidly upon re-exposure to an antigen
To initiate endocytosis and antigen degradation for presentation on MHC class II
To provide co-stimulatory signals for T cell activation and differentiation

Which of the following is a key feature of T-independent (TI) B cell activation?

It involves the crosslinking of B cell receptors by multivalent antigens (D) Signup and view all the answers

What is the role of immunoreceptor tyrosine-based activation motifs (ITAMs) in B cell signaling?

They initiate intracellular signaling cascades upon crosslinking of the B cell receptor (D) Signup and view all the answers

Which of the following is a key difference between T-dependent and T-independent B cell responses?

T-independent responses result in the production of high-affinity, class-switched antibodies (A) Signup and view all the answers

What is the primary function of B cells acting as antigen-presenting cells (APCs)?

To provide co-stimulatory signals for the activation and differentiation of CD4+ T cells (B) Signup and view all the answers

What is the primary role of phagocytes in the process of antigen presentation?

To degrade extracellular proteins into peptide fragments for loading into MHC molecules (C) Signup and view all the answers

Which pathway is responsible for the presentation of intracellular antigens?

MHC class I presentation pathway (B) Signup and view all the answers

What is the primary function of dendritic cells in the context of antigen presentation?

To act as phagocytes and present extracellular antigens via MHC class II molecules (D) Signup and view all the answers

What is the primary mechanism by which extracellular antigens are presented to CD4+ T cells?

Phagocytosis, degradation, and presentation on MHC class II molecules (C) Signup and view all the answers

Which of the following processes is involved in the presentation of intracellular antigens on MHC class I molecules?

Degradation in the cytosol and loading into MHC class I molecules (B) Signup and view all the answers

What is the primary function of pattern recognition receptors (PRRs) in the context of antigen presentation?

To sense potential threats and initiate the antigen presentation process (B) Signup and view all the answers

Which of the following statements accurately describes the process of macropinocytosis?

It is the process by which dendritic cells ingest and degrade extracellular material into peptides (D) Signup and view all the answers

Which statement about CD4+ T cell maturation is correct?

All of the above statements are correct. (D) Signup and view all the answers

What are the two possible pathways for differentiation of uncommitted Th0 cells?

Th1 cells that activate phagocytes and cytotoxic T cells, and Th2 cells that stimulate B cells to become plasma cells. (C) Signup and view all the answers

What is the first signal required for CD8+ T cell maturation?

Recognition of peptide-MHC class I complexes on the surface of infected cells or antigen-presenting cells (APCs). (D) Signup and view all the answers

What is the second signal required for CD8+ T cell maturation?

Release of interleukin-2 (IL-2) by activated CD4+ T cells, which binds to the IL-2 receptor on CD8+ T cells. (A) Signup and view all the answers

What is the outcome of CD8+ T cell maturation?

Differentiation into a clone of cytotoxic T-lymphocytes (CTLs) that release cytolytic granules. (C) Signup and view all the answers

Which of the following statements about T helper (Th) cells is incorrect?

Th cells are responsible for the production of antibodies. (A) Signup and view all the answers

What is the role of interleukin-2 (IL-2) in the maturation of CD8+ T cells?

IL-2 is secreted by CD4+ T cells and binds to the IL-2 receptor on CD8+ T cells, promoting their proliferation and differentiation. (A) Signup and view all the answers

Which molecule selects viruses and intracellular microbes for destruction by the proteasome?

Ubiquitin (B) Signup and view all the answers

What is the primary function of T cells in the adaptive immune response?

To act as the 'directors' of the adaptive immune response (B) Signup and view all the answers

What is the purpose of the immunologic synapse?

To stabilize the interaction between the antigen-presenting cell and the T cell (A) Signup and view all the answers

What is the purpose of the costimulatory molecules in T cell activation?

To provide the second signals required for T cell activation (C) Signup and view all the answers

What is the role of the CD3 complex in T cell signal transduction?

To form the pMHC:TCR:CD4 or 8 complex that provides the first signal for T cell activation (B) Signup and view all the answers

What is the purpose of the ITAMs (Immunoreceptor Tyrosine-based Action Motifs) in T cell signal transduction?

To initiate the signaling cascade in the T cell (B) Signup and view all the answers

What is the primary function of T cell receptors (TCRs)?

To recognize peptides presented by MHC Class I or II molecules on antigen-presenting cells (A) Signup and view all the answers

What is the primary function of lipopolysaccharides (LPS) in the context of T-dependent B cell activation?

LPS provides repetitive epitopes that facilitate the engagement of B cell receptors (BCRs). (D) Signup and view all the answers

Which of the following signals is NOT involved in the initial activation of B cells during a T-dependent response?

Secretion of IL-4 by the Th cell. (D) Signup and view all the answers

What is the primary role of IL-4 in the T-dependent B cell activation process?

IL-4 induces the expression of IL-4 receptors on B cells, allowing for their proliferation and differentiation. (D) Signup and view all the answers

Which of the following statements accurately describes the role of plasma cells in the T-dependent B cell response?

Plasma cells secrete immunoglobulins with the same specificity as the original B cell surface immunoglobulins. (B) Signup and view all the answers

What is the primary function of memory B cells in the T-dependent B cell response?

Memory B cells are long-lived cells that are ready to encounter the same epitope at a later date. (A) Signup and view all the answers

Which of the following statements accurately describes the role of T cells in the T-dependent B cell activation process?

T cells provide co-stimulatory signals to B cells through the engagement of co-stimulatory molecules. (C) Signup and view all the answers

Which of the following statements accurately describes the T-dependent B cell activation process?

T-dependent B cell activation is initiated by the engagement of the BCR with an epitope, followed by co-stimulatory signals from T cells and the secretion of IL-4. (D) Signup and view all the answers

Which of the following statements accurately describes the role of co-stimulatory molecules in the T-dependent B cell activation process?

Co-stimulatory molecules provide internal signaling to both T and B cells, which is necessary for their activation. (A) Signup and view all the answers

Which of the following statements accurately describes the role of the T cell receptor (TCR) in the T-dependent B cell activation process?

The TCR engages with a peptide-MHC class II complex, providing a signal for T cell activation and subsequent co-stimulation of B cells. (D) Signup and view all the answers