Immunological memory

Question 1

where are short-lived plasma cells located?

Answer 1

They reside in the lymph node or spleen

Question 2

where are long-lived plasma cells located?

Answer 2

They reside in the bone marrow where they receive survival signals from stromal cells

Question 3

what is the function of long-lived plasma cells?

Answer 3

They are a source of long-lasting high-affinity class-switch antibody

Question 4

what are plasma cells?

Answer 4

Antibody factories

Question 5

where do memory B cells come from?

Answer 5

they arise from the germinal centre reaction

Question 6

what are the features of memory B cells?

Answer 6

they have inherited the genetic changes from the germinal centre reaction
- express high-affinity antibody
- have undergone antibody class switching

They express higher levels of MHC II and co-stimulatory molecules than naive B cells

Question 7

where are memory B cells found?

Answer 7

They populate the spleen and lymph nodes and circulate through the blood

Question 8

how do memory B cells express antibody?

Answer 8

Express surface Ig but do not secrete antobody

• Quickly generate antibody producing plasma cells when they re-encounter antigen

Question 9

what do most vaccines rely on?

Answer 9

B cell memory

Question 10

what are memory T cells?

Answer 10

long-libed cells that survive after the contraction of the effector phase

Question 11

what is needed for survival of memory T cells?

Answer 11

IL-7 and IL-15
- memory T cells also need to contact self-peptide:self MHC complexes to continue to proliferate (does not need to be specfic antigen)

Question 12

what are the features of memory T cells?

Answer 12

-Higher precursor frequency
- Different activation requirements and cell surface proteins from naive and effector cells

• Memory T cells divide more frequently than naive T cells
• Memory pool size is dictated by a balance between cell proliferation and cell death

Question 13

what do memory T cells need to be effective?

Answer 13

• know where to go
• Be able to get there quickly or already be there
• Have good fighter equipment

Question 14

what are the differences between memory T cells and effector T cells?

Answer 14

• They proliferate more than naive T cells and to a lower level of antigen dose
• Require less co-stimulation for activation than naive cells
• Produce cytokine faster and retain their polarised phenotype
• May be strategically positioned in the tissue where the pathogen is likely to be encountered

Question 15

what are the features of central memory?

Answer 15

-Express lymph-node homing molecules
- Slower than effector memory cells to produce cytkine

Question 16

what are the features of effector memory?

Answer 16

-lack lymph-node homing molecule expression
- rapidly produce cytokine upon antigenic stimulation

Question 17

what are lymph noe homing molecules and where are they expressed?

Answer 17

Lymph node homing molecules CCR7 and CD62L are co-expressed on a subset of CD4 and CD8 memory T cells in human peripheral blood

Question 18

what are Tcm and Tem cell subsets?

Answer 18

Tcm is CCR7+ (not very good at making cytokine)
Tem is CCR7-

Question 19

what is the difference between Tcm and Tem cell subsets?

Answer 19

Tem persist in tissue and are functionally superior to Tcm
- discovery that after viral or bacterial infection memory CD8 T cells moved to non-lymphoid tissues and remained as long-lived memory cells. These cells were more lytic than memory CD8 T cells from the spleen

Question 20

what are the features of tissue resident memory?

Answer 20

-Lack lymph-node homing molecule expression, express the integrin CD103 and CD69. Do not recirculate in the blood.
- Rapidly produce cytokine upon antigenic stimulation

Question 21

how where Trm T cells discovered?

Answer 21

Discovery that after infection memory CD8+ T cells can remain in tissues after infection has cleared without recirculating in the blood

Question 22

where do you not find resident memory T cells?

Answer 22

in the blood

Question 23

what is the linear model of memory T cell development?

Answer 23

Memory cells develop directly from differentiated effector cells

Question 24

what is the evidence that supports the linear model of memory T cell development?

Answer 24

Adoptive transfer studies show adoptively transferred effect CD4 and CD8 T cells develop into memory populations that retain similar functional polarisation to the effect cells

Question 25

what is the progressive model of memory T cell development?

Answer 25

The degree of activation dictates the fate of a cell

Question 26

what evidence supports the progressive model of memory T cell development?

Answer 26

transcriptional profile analysis of naive, memory, and effector CD8 T cells generated after vaccination, suggest cumulative antigen stimulation drives naive T cells to differentiate into memory T cells, then into terminally differentiated effector T cells

Question 27

what is the divergent model of memory T cell development?

Answer 27

T cells are destined to an effector or memory lineage due to asymmetric cell division

Question 28

what supports the divergent model of memory T cell development?

Answer 28

clustering of receptors and molecules at the immunological synapse causes uneven distribution of cell contents in daughter cells

Question 29

what is innate immune ‘memory’?

Answer 29

Epigenetic changes in monocytes result in a long-lasting enhanced protection against infection

Question 30

what is the evidence for innate immune ‘memory’?

Answer 30

many vaccines have effects that extend beyond the targeted disease