Lecture 06: T-cells and B-cell activation [MCQ 2]

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Questions and Answers

Which of the following is the primary function of cytotoxic T cells (Tc cells)?

To present antigens to helper T cells (Th cells) on MHC Class II molecules.

To activate other immune cells, such as macrophages and B cells, through the release of cytokines.

To directly kill infected or cancerous cells by releasing granzymes and perforin. (correct)

To produce antibodies that target specific antigens present on the surface of pathogens.

Which of the following is NOT a key role of helper T cells (Th cells) in the immune response?

To stimulate B cells to differentiate into plasma cells and memory cells.

To directly kill infected cells by releasing cytotoxic molecules. (correct)

To activate cytotoxic T cells (Tc cells) to proliferate and eliminate infected cells.

To secrete cytokines that activate macrophages to become more effective phagocytes.

Which of the following statements accurately describes the process of antigen presentation on MHC Class II molecules?

MHC Class II molecules present antigens derived from intracellular pathogens that have been processed by the proteasome.

MHC Class II molecules are expressed on all nucleated cells in the body and present antigens derived from intracellular pathogens.

MHC Class II molecules are expressed primarily on antigen-presenting cells (APCs) like dendritic cells and macrophages and present antigens derived from extracellular pathogens. (correct)

MHC Class II molecules are expressed on the surface of T cells and present antigens to B cells to stimulate antibody production.

When an infected cell presents an antigen on MHC Class I, how does a cytotoxic T cell recognize and respond?

The cytotoxic T cell binds to the antigen-MHC Class I complex using its TCR, leading to the release of cytotoxic molecules like granzymes and perforin, ultimately killing the infected cell. (C) Signup and view all the answers

What is the primary function of the proteasome in the process of antigen presentation on MHC Class I molecules?

The proteasome degrades foreign proteins from intracellular pathogens into smaller peptide fragments. (C) Signup and view all the answers

Which of the following is NOT a characteristic of naive T cells and B cells before they encounter an antigen?

They have already differentiated into effector cells with specialized functions, such as antibody production or cytotoxic activity. (A) Signup and view all the answers

Why is the activation of helper T cells (Th cells) crucial for the development of a robust immune response?

Th cells activate other immune cells, like macrophages and B cells, leading to a coordinated attack against the pathogen. (A) Signup and view all the answers

How does the HIV virus primarily disrupt the immune system?

HIV infects and destroys helper T cells (Th cells), leading to a compromised immune system unable to effectively mount a response. (A) Signup and view all the answers

Which of the following is an accurate description of the role of antigen-presenting cells (APCs) in T-cell activation?

APCs process and present antigens from pathogens to T cells, initiating the immune response. (C) Signup and view all the answers

What is the primary role of memory T cells produced during an immune response?

Memory T cells provide long-lasting immunity by quickly recognizing and responding to specific antigens upon re-exposure, promoting a faster and more effective immune response. (D) Signup and view all the answers

Which of the following accurately describes the process of antigen recognition and activation of T cells within a lymph node?

T cells primarily search for dendritic cells (DCs) that have processed and presented antigens on their MHC Class II molecules. (B) Signup and view all the answers

How do B cells primarily encounter antigens within a lymph node?

B cells passively filter lymph fluid, encountering antigens that are small and soluble. (C) Signup and view all the answers

What is the primary function of lymph node macrophages in the context of antigen recognition?

Lymph node macrophages engulf and destroy viruses and very large antigens, preventing their spread. (A) Signup and view all the answers

What specific event leads to the activation of a B cell, resulting in its differentiation into a plasma cell?

The B cell encounters a T helper (Th) cell that recognizes the same antigen presented by the B cell on its MHC II molecule. (A) Signup and view all the answers

Which of the following is NOT a step involved in the activation of a B cell within a lymph node?

B cells directly bind to antigens in the lymph fluid, triggering their activation. (B) Signup and view all the answers

What is the approximate timeframe for the activation and proliferation of a B cell into a plasma cell within a lymph node?

4-7 days after encountering an antigen. (B) Signup and view all the answers

What is the primary role of the class switching process in B cell activation?

Class switching allows B cells to produce different types of antibodies, including IgM, IgG, IgA, IgE, and IgD. (C) Signup and view all the answers

What is the primary difference between T cell activation and B cell activation within a lymph node?

T cells directly bind to antigens in the lymph fluid while B cells require interaction with antigen-presenting cells (APCs) like DCs. (B) Signup and view all the answers

What is the fate of a T cell that does not encounter its specific antigen within a lymph node within a 24-hour period?

The T cell migrates to the next lymph node in the lymphatic system, continuing its search. (A) Signup and view all the answers

What is the approximate number of plasma cells that a single activated B cell gives rise to during differentiation?

5000 plasma cells. (C) Signup and view all the answers

Flashcards

T-cells

White blood cells that mature in the thymus and recognize antigens.

Cytotoxic T cells

CD8 T-cells that kill cancerous or infected cells.