[W9] Memory cells: what makes a memory cell “remember”? Flashcards
(32 cards)
What is immunological memory?
The ability of the adaptive immune system to respond faster and more effectively to previously encountered pathogens.
Which cells are responsible for immunological memory?
Memory T cells and Memory B cells.
Why is immunological memory important?
It provides long-term protection and is the basis for vaccination.
What are two theories on how memory cells form?
- Some effector cells resist apoptosis
- Memory cells develop independently during activation
Do memory cells require persistent antigen for survival?
Possibly – some evidence suggests survival signals from follicular dendritic cells (FDCs) may help.
Are FDCs derived from bone marrow?
No – they are not bone marrow-derived or phagocytic.
What is a key role of FDCs in memory?
They may retain antigens on their surface to support B cell memory.
Where are memory B cells and long-lived plasma cells found?
- MBCs: Secondary lymphoid organs
- LLPCs: Bone marrow
Do memory B cells secrete antibody?
No – they only produce antibody after reactivation.
What is the function of LLPCs?
Continuously secrete antibody without dividing.
Which transcription factors are involved in memory B cell formation?
PAX-5 and MITF.
Which transcription factors drive plasma cell fate?
Blimp-1, XBP-1, IRF-4.
What antibody isotypes are associated with memory B cells?
Class-switched antibodies (e.g., IgG, IgA, IgE).
Do memory B cells express surface BCRs?
Yes – they have high-affinity BCRs.
What are the two major subsets of memory T cells?
- Effector Memory T cells (TEM)
- Central Memory T cells (TCM)
Where are TCM cells found?
Secondary lymphoid tissues (e.g., lymph nodes).
What markers define TCM cells?
CD62L+ and CCR7+.
Where are TEM cells found?
In peripheral tissues and some lymphoid organs.
What markers define TEM cells?
CD62L− and CCR7−.
What is the divergent pathway model?
Activated cells take separate fates (effector or memory) based on signals.
What is the linear model?
Memory cells arise from effector cells after contraction.
What does the ‘decreasing potential’ model suggest?
Long exposure to antigen reduces memory potential due to exhaustion.
What makes memory T cells respond more quickly?
- Preloaded with cell cycle regulators
- Altered TCR signalling
- Strategic tissue localisation
- Epigenetic modifications of key genes
Can memory T cells change subtype (e.g., Th1 ↔ Th2)?
Mostly pre-programmed, but limited plasticity may exist.
