Question 1

What event initiates an adaptive immune response?

Accepted Answer

The initiation of an adaptive immune response begins when a naïve T cell interacts with an antigen-presenting cell (APC) such as a dendritic cell, which presents an antigen to the T cell via MHC molecules. This interaction is crucial for the activation of T cells, which then proliferate and differentiate to perform their roles in the immune response.

Question 2

Which of the following molecules provide costimulatory signals to naïve T cells?

Accepted Answer

CD28 and ICOS both provide costimulatory signals to naïve T cells, which are essential for their activation and function. CTLA-4 and PD-1, on the other hand, are involved in inhibiting T cell responses.

Question 3

For pathogen peptides to be seen as foreign, they must be displayed on a T cell in the context of a(an)

Accepted Answer

Pathogen peptides are presented to T cells in the context of Major Histocompatibility Complex (MHC) molecules, which are essential for T cell recognition and immune response activation.

Question 4

CD4⁺ T cells recognize

Accepted Answer

CD4+ T cells recognize peptides presented by MHC class II molecules.

Question 5

CD8⁺ T cells exposed to MHC class I peptides are

Accepted Answer

CD8+ T cells exposed to MHC class I peptides become cytotoxic T cells, which are responsible for killing infected or cancerous cells.

Question 6

CD4⁺ T cells become helper T cells in response to

Accepted Answer

CD4⁺ T cells become helper T cells when they recognize antigens presented by MHC class II molecules on antigen-presenting cells.

Question 7

Naïve CD4⁺ and CD8⁺ T-cells leave the _____ and enter circulation.

Accepted Answer

Naïve CD4 and CD8 T-cells, after their development and maturation in the thymus, leave the thymus to enter the circulation and perform their immune functions.

Question 8

A naïve T-cell refers to a T cell that

Accepted Answer

Naïve T cells are those that have matured and left the thymus but have not yet encountered their specific antigen.

Question 9

Bonds formed between the T cell and a dendritic cell are relatively weak.Which of the following help to strengthen this association so that a T cell can see which antigen is being presented by a dendritic cell?

Accepted Answer

ICAM-1/LFA-1 interaction helps to strengthen the bond between T cells and dendritic cells, facilitating the T cell's ability to recognize the antigen being presented.

Question 10

Which of the following is required for T-cell activation?

Accepted Answer

T-cell activation requires both antigen-specific TCR (T-cell receptor) binding to MHC (Major Histocompatibility Complex) peptide and co-stimulatory signals, such as the interaction with CD80, CD86, or ICOS-L on antigen-presenting cells.

Question 11

Coreceptor molecules are required by T_C and T_H cells so that the TCR can stably bind to the MHC peptide presenting the antigen.All of the following are coreceptor molecules common to both T_C and T_H cells and their respective antigen-presenting cells EXCEPT

Accepted Answer

The answer of Coreceptor molecules are required by T_C and...

Question 12

CTLA-4 is a costimulatory receptor on T cells that belongs to the same family as the CD28 costimulatory receptor.However, CTLA-4 is antagonistic to CD28.Which of the following could be a functional advantage of CTLA-4 expression within the immune response?

Accepted Answer

CTLA-4 acts as an inhibitory receptor that can dampen the immune response once an infection has been cleared, preventing excessive or prolonged activation that could lead to tissue damage or autoimmunity.

Question 13

PD-1 is a negative costimulatory signal expressed by tumor cells.What advantage would the expression of PD-1 have in a tumor cell avoiding the immune response?

Accepted Answer

PD-1 expression on tumor cells can inhibit the activity of activated T cells, allowing the tumor cells to evade immune detection and destruction.

Question 14

T cells are frequently at fault for causing damage in autoimmune disorders and in transplant rejection.As an immunologist, your dream is to discover a method for decreasing T-cell response to self-antigens.Which of the following would be the BEST target for your research?

Accepted Answer

Ligands that block the binding of one costimulatory molecule would be the best target for research aimed at decreasing T-cell response to self-antigens. This approach can specifically inhibit the activation of T cells without broadly suppressing the immune system, potentially reducing autoimmune responses and transplant rejection.

Question 15

T-cell activation requires antigen being displayed in the context of an APC and interaction between costimulatory molecules on the APC and the T cell.In addition to these two signals, T-cell activity is often influenced by cytokines.Which of the following is an example of how cytokines can influence T-cell activity in the presence of MHC presentation and costimulatory ligand interaction?

Accepted Answer

IL-2 is a cytokine that plays a crucial role in the proliferation of T cells once they have been activated by antigen presentation and costimulatory signals.

Question 16

Which type of professional antigen-presenting cells is a naïve T cell MOST likely to encounter?

Accepted Answer

The answer of Which type of professional antigen-presenting cells is...

Question 17

TSST-1 is a protein produced by some species of bacteria that acts as a superantigen.What ligand does TSST-1 bind?

Accepted Answer

TSST-1 binds to both the T-cell receptor (TCR) and MHC class II molecules. This cross-linking leads to the massive activation of T-cells, characteristic of the superantigen effect.

Question 18

With respect to T-cell activation, effector molecules trigger all of the following functions EXCEPT

Accepted Answer

T-cell activation primarily involves cell-cycle entry, division, differentiation, and survival. The direct stimulation of B cells is not a primary function of effector molecules in T-cell activation; instead, this is a function of helper T cells through different mechanisms.

Question 19

Which helper T-cell subset is MOST likely to be preferentially generated in response to a virus?

Accepted Answer

The answer of Which helper T-cell subset is MOST likely...

Question 20

Which type of T cell directs and regulates B-cell activity and differentiation?

Accepted Answer

T_H2 cells are a subset of helper T cells that play a crucial role in directing and regulating B-cell activity and differentiation, particularly in the production of antibodies.

Quiz 10: T-Cell Activation, Differentiation, and Memory