Adaptive Immunity Flashcards

1
Q

how long can the adaptive immune response take to activate

A

days - weeks

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2
Q

what is the first thing lymphocytes do after antigen binding

A

enter the cell division cycle to divide by mitosis and expand their population

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3
Q

which two types of cells do lymphocytes differentiate into after clonal expansion

A

memory cells
effector cells

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4
Q

what two major zones are lymph nodes organised into

A

B cell follicles around the edges
T cell zone in the middle

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5
Q

where do B cells get activated by antigens

A

lymph nodes

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6
Q

which chemokine helps with the expression of co-stimulatory molecules when dendritic cells are displaying MHC-peptide complexes

A

TNF alpha

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7
Q

explain how high endothelial venules allow lymphocytes to escape blood vessels and enter the lymph system

A

they constitutively express all of the necessary adhesion molecules to attach to the lymphocytes allowing transepithelial migration
(similar to how neutrophils enter infected tissues)

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8
Q

what do accessory molecules do

A

stabilise the interaction of APCs and TCRs and provide co-stimulation

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9
Q

what type of cells are in the B cell zone of lymph nodes

A

stromal cells that can be enriched for the expression of opsonin receptors

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10
Q

explain T cell-independent B cell activation

A

long chain carbohydrate binds
BCR clustering
not as efficient as T cell dependant
can only produce IgM - low/medium affinity
memory cells not created
smaller amounts of IL-2

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11
Q

explain T cell-dependant B cell activation

A

TCR binds MHC II along with co-stimulatory molecule binding
large amounts of IL-2

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12
Q

what does the differentiation of lymphocytes depend on

A

cytokine environment

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13
Q

what epitopes can T-cells respond to

A

only peptides

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14
Q

what epitopes can B-cells respond to

A

anything

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15
Q

what two things related to IL-2 do activated T-cells do

A

upregulates the transcription and translation of IL-2
increases the expression of the high-affinity subunits of the IL-2 receptor

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16
Q

what does IL-2 binding lead to

A

entry into the cell cycle and clonal expansion

17
Q

what is the primary source of IL-2

A

activated CD4 T cells

18
Q

what is the T-helper nought state

A

T helper cells are activated and have proliferated but not yet fully differentiated

19
Q

what dictates the cytokine environment

A

the pathogen causing the response

20
Q

what are CD4 TH4 cells

A

effector T helper cells which secrete IFN gamma which favours macrophage activation and cell-mediated responses

21
Q

what are CD4 TFH (T follicular helper cells)

A

effector T helper cells which secrete IL-21 which stimulates B cell activation within the lymph node

22
Q

what is the role of TH1 cells?

A

effector T helper cells which use co-stimulation to hyperactivity macrophages, enhancing their activity (killing, TNF alpha secretion)

23
Q

what are the primary targets of cytotoxic T cells?

A

virally infected cells
cells infected with intracellular pathogens

24
Q

explain the cytotoxic T-cell granule-killing mechanisms

A

they contain granules full of toxic proapoptotic-inducing factors
the contents of these granules are released into the target cell via a narrow cleft (prevent killing of surrounding healthy cells)

25
Q

why is T cell activation switched off during a prolonged infection?

A

limit bystander tissue damage