BIOS 490 3rd Quarter

Which of the following best describes immunological memory?

The ability of the adaptive immune system to retain a subset of T and B cells after pathogen elimination

Which cytokine is most critical for the long-term survival of memory T cells?

IL-7

What distinguishes central memory T (TCM) cells from other memory T cell subsets?

They express L-selectin (CD62L) and CCR7 for circulation through the T-cell zone

Tissue-resident memory T (TRM) cells are most commonly found in which locations?

Skin and gastrointestinal tract

Which of the following best describes the primary function of IL-7 in memory T cell survival?

Prevents clonal contraction by promoting memory T cell longevity

What is a key difference between the linear and branching models of memory T cell formation?

The linear model states that memory T cells arise from effector T cells

Effector memory T (TEM) cells differ from central memory T (TCM) cells in that they:

Express β1 and β2 integrins for entry into inflamed tissues

Which of the following statements about memory T cell survival is correct?

IL-7R expression is reduced in effector T cells, leading to apoptosis

A researcher isolates a subset of T cells expressing high levels of L-selectin (CD62L) and CCR7. These cells are most likely:

Central memory T cells

How do tissue-resident memory T (TRM) cells remain localized in their respective tissues?

Cytokines from epithelial cells induce adhesion proteins to anchor them in place

In a study, a patient who recovered from a viral infection 75 years ago still has detectable memory T cells against the virus. What does this suggest about immunological memory?

Immunological memory can persist for decades after exposure

What feature allows effector memory T (TEM) cells to enter inflamed tissues?

Expression of β1 and β2 integrins

Which of the following cells is least likely to express high levels of IL-7 receptor (IL-7R)?

Effector T cells

What would likely happen to memory T cells if IL-7 signaling were completely blocked?

Memory T cells would undergo apoptosis over time

Which of the following is the primary function of immunological memory in the adaptive immune system?

To allow the immune system to respond more rapidly and effectively upon re-exposure to a pathogen

Studies have found memory T cells that persisted for how long after pathogen exposure?

75 years

What is the key difference between the linear and branching (asymmetric division) models of memory T cell formation?

The linear model proposes that memory T cells arise directly from effector T cells, while the branching model suggests they form independently upon naïve T cell activation.

Which of the following findings challenges the traditional linear model of memory T cell formation?

Some effector T cells can dedifferentiate into memory T cells following epigenetic rearrangement.

Which subset of memory T cells recirculates between the blood, secondary lymphoid organs, and lymph?

Central memory T (TCM) cells

What feature distinguishes tissue-resident memory T (TRM) cells from other memory T cell subsets?

They are confined to a single tissue and do not recirculate.

Which of the following best describes the movement of effector memory T (TEM) cells?

They either remain in the blood or recirculate between tissues, lymph, lymph nodes, and blood.

What is the primary function of L-selectin (CD62L) and CCR7 in central memory T (TCM) cells?

They allow TCM cells to circulate through the T-cell zones of secondary lymphoid organs.

Which type of membrane protein is primarily responsible for effector memory T (TEM) cell migration into inflamed tissues?

β1 and β2 integrins

Why are TRM cells particularly abundant in barrier tissues such as the skin and gastrointestinal tract?

These sites are frequently exposed to pathogens, necessitating local immune surveillance.

Which cytokine is most critical for the long-term survival of memory T cells?

IL-7

What happens to effector T cells that do not upregulate IL-7R after pathogen clearance?

They undergo apoptosis due to the lack of survival signals.

Which of the following cell types produces IL-7 to support memory T cell survival?

Fibroblastic reticular cells in the T cell zone

Why do naïve T cells and memory T cells both express high levels of IL-7R?

To ensure their survival in the absence of antigen stimulation

Which cytokine, alongside IL-7, plays a role in the long-term survival of memory T cells?

IL-15

How do memory T cells maintain long-term survival in the absence of persistent antigen exposure?

They receive cytokine signals such as IL-7 and IL-15

Which metabolic pathway is primarily utilized by memory T cells to meet their energy demands?

Fatty acid oxidation

Compared to naïve T cells, memory T cells are characterized by which of the following?

Higher expression of co-stimulatory receptors like CD28

How can memory B cells be distinguished from naïve B cells?

Memory B cells have undergone isotype switching

Which of the following statements best describes the fate of memory B cells following antigen re-exposure?

They immediately release antibodies of the same isotype formed in the primary response

What is the significance of somatic hypermutation in memory B cells?

It increases antibody affinity over time with each antigen exposure

Where do memory B cells primarily reside when not circulating in the bloodstream?

The spleen and lymph nodes

Which of the following is true regarding isotype switching in B cells?

It requires signaling from TFH cells

Which metabolic characteristic differentiates effector T cells from memory T cells?

Effector T cells have a high demand for energy and primarily use glycolysis

What is the role of TFH cells in memory B cell formation?

They induce signals that promote isotype switching and they provide cytokines required for somatic hypermutation

Which of the following best explains why memory T cells persist long after an infection is cleared?

They express high levels of IL-7R, allowing them to receive survival signals

Which of the following metabolic characteristics best describes memory T cells compared to naïve and effector T cells

A switch to fatty acid oxidation while maintaining high oxidative phosphorylation potential

A researcher isolates a subset of T cells that require less energy than effector T cells but are highly sensitive to restimulation. These cells also express high levels of CD28. What type of T cells are they most likely to be?

Memory T cells

Which of the following best explains why memory B cells respond more rapidly upon secondary antigen exposure?

They have already undergone isotype switching and somatic hypermutation

A patient is exposed to a pathogen for the second time. Which antibody is most likely to be produced in large quantities?

IgG

Isotype switching in B cells occurs primarily in which location?

Germinal centers

Which process is responsible for increasing the affinity of antibodies after multiple antigen exposures?

Somatic hypermutation

A scientist is studying memory B cell formation and finds that some memory B cells are generated before entering germinal centers. What does this suggest?

Germinal centers are required for isotype switching, but not for all memory B cell formation

A mutation in the TFH cell population impairs its ability to send activation signals to B cells. Which of the following processes would most likely be disrupted?

Memory B cell formation

Which of the following statements about memory T cells is TRUE?

IL-7 is a crucial survival signal for memory T cells

In the absence of IL-7 signaling, what would most likely happen to memory T cells?

They would undergo apoptosis

Tissue-resident memory T cells (TRM) are most commonly found in which locations?

Barrier tissues such as the skin and gastrointestinal tract

What allows TRM cells to remain in their respective tissues?

Adhesion molecules induced by epithelial cell cytokines

A researcher identifies a population of memory T cells that express L-selectin (CD62L) and CCR7, allowing them to recirculate between blood and lymphoid organs. These are most likely:

Central memory T cells (TCM)

Which of the following is a defining characteristic of effector memory T cells (TEM) compared to other memory T cell subsets?

They express β1 and β2 integrins, allowing entry into inflamed tissues

A scientist is studying a population of B cells that have undergone isotype switching but still retain the ability to undergo affinity maturation with repeated antigen exposures. These are most likely:

Memory B cells

What is the "dedifferentiation" model of memory T cell formation, and how does it challenge the traditional linear model?

It proposes that effector T cells can revert to a memory-like state instead of terminal differentiation.

Which experimental evidence supports the idea that effector T cells can revert to memory T cells rather than following a strict differentiation pathway?

Observations of effector T cells regaining IL-7R expression and persisting as memory cells.

Which chemokine receptors are critical for TRM cell migration to different tissues?

CCR5 and CXCR6

How do TRM cells remain in peripheral tissues without recirculating?

They lose expression of S1PR1, preventing exit from tissues.

Which specific cell types produce IL-7, and how does this support memory T cell survival?

Fibroblastic reticular cells, epithelial cells, and stromal cells; they provide survival signals.

Why is IL-7 production restricted to non-hematopoietic cells like epithelial and fibroblastic reticular cells?

IL-7 needs to be available continuously, and immune cells have short lifespans.

How does the metabolism of naïve, effector, and memory T cells differ?

Naïve: low energy demand; Effector: high glycolysis & oxidative phosphorylation; Memory: fatty acid oxidation

Why do memory T cells rely more on fatty acid oxidation compared to effector T cells?

It allows them to survive in low-glucose environments and maintain longevity.

What role does mitochondrial biogenesis play in memory T cell longevity?

It increases the ability to generate ATP efficiently, supporting long-term survival.

How do memory B cells circulate before finding a long-term residence in lymphoid organs?

They home to lymphoid organs based on chemokine receptor expression.

What signals determine whether memory B cells remain in circulation or settle in secondary lymphoid tissues?

Presence of inflammatory cytokines and antigen-specific interactions

At what stages in germinal center reactions can memory B cells be generated?

Both before and after entering germinal centers

How do memory B cells formed before entering the germinal center differ from those that develop later?

Early memory B cells lack somatic hypermutation.

Describe the pattern of IL-7R expression in T cells from naïve to memory stages.

High in naïve → decreases in effectors → increases in memory

Why does IL-7R expression decrease in effector T cells but reappear in memory T cells?

Effector T cells downregulate IL-7R due to activation, but memory T cells need it for survival.

What makes memory T cells more sensitive to restimulation compared to naïve T cells?

Higher expression of co-stimulatory receptors like CD28

How does increased CD28 expression contribute to memory T cell responsiveness?

It enhances co-stimulation, allowing for faster activation upon antigen recognition.