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IBI Test 4 > B3.039 Prework 1 Immune Cell Development > Flashcards

B3.039 Prework 1 Immune Cell Development Flashcards

1
Q

what defines a naïve lymphoid cell

A

express antigen receptors, but cannot do anything

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2
Q

where are naïve lymphoid cells located?

A

circulate amongst peripheral lymphoid organs

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3
Q

describe the life cycle of naïve lymphoid cells

A

survey for antigens and differentiate upon exposure into memory and effector cells
undergo apoptosis if they don’t find their antigen within weeks to months
new cells are released

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4
Q

what defines a B Cell effector cell

A

produce molecules that eliminate antigens

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5
Q

function of plasma cells

A

produce Abs in the peripheral lymphoid tissues

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6
Q

function of plasmablasts

A

produce Abs in the blood stream

some migrate to the bone marrow to mature into plasma cells

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7
Q

function of T Cell effector cells

A

produce molecules that eliminate antigens

short lived and die after elimination of antigen

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8
Q

function of CD4+ T helper cells

A

produce cytokines to activate B cells, macrophages, and others

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9
Q

function of CD8+ cytotoxic cells

A

kill infected host cells

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10
Q

what are lymph nodes

A

encapsulated aggregates of lymphoid tissue

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11
Q

what is lymph

A

leakage from blood vessels

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12
Q

function of lymphatic vessels

A

carry the lymph that has drained from the tissues to the lymph nodes

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13
Q

discuss the role of the lymphatic system in immunity

A

APCs sample the lymph for antigens of microbes
dendritic cells capture antigens and transport them to the lymph node via the afferent vessel
exit lymph node via the efferent lymphatic vessel

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14
Q

where are follicles located in the lymph node

A

cortex

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15
Q

what is located in cortex follicles

A

B cells- periphery/cortex

follicular dendritic cells

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16
Q

where are germinal centers located

A

middle of follicles

light staining areas

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17
Q

what is located in germinal centers

A

B cells that have recently responded to an antigen

site of antibody production

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18
Q

what is located in the paracortex of the lymph nodes

A

T cells adjacent to the follicles

dendritic cells

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19
Q

discuss the circulation of naïve T and B lymphocytes

A

constantly circulate between blood and lymphoid organs where they enter through a high endothelial venule (HEV)
chemokines home them to their respective area

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20
Q

CXCR5

A

receptor on B cells that homes them to the follicle

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21
Q

CCR7

A

receptor on T cells that homes them to the paracortex

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22
Q

discuss the circulation of dendritic cells

A

enter through afferent lymphatic vessels

migrate to the T cell rich areas of the node

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23
Q

how are lymphocytes activated upon stimulation by antigen

A

change chemokine receptors
T and B cells can move toward each other and meet at the follicular edge to interact
T cells help B cells differentiate into Ab producing cells

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24
Q

what happens after lymphocytes are activated

A

exit through the efferent lymphatic vessels to travel to sites of infection
some T cells migrate into the follicle to help B cells make high affinity Abs

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25
Q

where are plasma cells located

A

peripheral lymphoid tissue and bone marrow

do not migrate to sites of infection

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26
Q

function of plasma cells

A

secrete Abs into the blood stream and onto mucosal surfaces to bind microbes or their toxins

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27
Q

what cells do migrate to sites of infection

A

effector T cells

other memory T cells will recirculate in the lymph nodes

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28
Q

function of spleen white pulp

A

trap pathogens and their secreted antigens that have entered the blood stream and present them to naïve lymphocytes passing through
pathogens are coated by Abs generated in the white pulp

29
Q

function of spleen red pulp

A

filters and removes microorganisms via phagocytes that recognize the Ab or complement coated microorganism directly
filters blood to remove abnormal or old RBCs

30
Q

PALS

A

periarteriolar lymphoid sheath
surrounds splenic arteriole
made up of T cells

31
Q

what makes up the white pulp

A

PALS and lymphoid follicles together

32
Q

where are vascular sinusoids

A

red pulp

33
Q

what is the mantle zone

A

ring of lymphocytes surrounding the germinal center

34
Q

what is the marginal zone

A

interface between the red pulp and the white pulp where particulate antigen from circulation is trapped and presented to APCs

35
Q

GALT

A

gut associated lymphoid tissue

secondary lymphoid tissue

36
Q

function of GALT

A

trap pathogens and their secreted antigens that have entered through the GI tract
presentation to naïve lymphocytes passing through

37
Q

what creates the innate barrier of the GALT

A

mucus secreting epithelium

38
Q

where is gut commensal bacteria located

A

stays in the lumen

39
Q

what are M cells

A

specialized epithelial cells that promote antigen transportation to underlying tissues

40
Q

where do lymphoid cells encounter antigen in the GALT

A

lamina propria

41
Q

Peyer’s patches

A

organized areas of lymphoid aggregates

42
Q

which Ig is associated with the GALT

A

IgA transports into the lumen to neutralize microbes

43
Q

what prevents reactions to commensal microbes

A

T reg cells and others suppress T lymphocyte activation

44
Q

25% of the body’s lymphocytes are in these areas at any given time

A

GALT/ MALT/ cutaneous lymphoid tissue

45
Q

makeup and function of the thymus cortex

A

immature T lymphocytes differentiate
undergo selection
reticular epithelial network

46
Q

makeup and function of the thymus medulla

A

less T lymphocytes

undergo further selection and mature prior to leaving

47
Q

what is Hassal’s corpuscles

A

within the medulla

flat keratinized degenerate epithelial cells

48
Q

what are the two primary steps in IgH rearrangement

A

1st: D to J recombination
2nd: V to DJ

49
Q

what is V(D)J recombinase

A

group of enzymes that mediate recombination

lymphocyte specific enzymes and ubiquitously expressed enzymes

50
Q

what are the primary lymphocyte specific enzymes in V(D)J recombinase

A

recombination-activating gene-1 and -2 (RAG-1 and RAG-2)

terminal deoxynucleotidyl transferase (TdT)

51
Q

what are the ubiquitously expressed enzymes in V(D)J recombinase

A

DNA ligase IV

DNA-PK

52
Q

combinatorial diversity

A

mediated by RAG-1/2
many combination of Vs, Ds, and Js can be used
D>J followed by V>DJ

53
Q

junctional diversity

A

mediated by TdT

addition/subtraction of nucleotides at the coding joint

54
Q

describe B cell receptor editing

A

the autospecific B cell undergoes a second K/L locus rearrangement
second rearrangement replaces the L chain of the self reactive BCR
B cell undergoes another round of selection based on its new BCR

55
Q

negative selection

A

if BCR editing does not succeed, cells apoptose

most immature B cells die

56
Q

positive selection

A

become mature naïve B cells

must co-express IgM and IgD

57
Q

pro-B cells

A

express RAG-1/RAG-2 and TdT

58
Q

pre-B cells

A

express IgM + surrogate light chain

re-express RAG-1 and RAG-2

59
Q

immature B cells

A

express IgM+ K or L chain

subject to selection or deletion, MOST immature cells die

60
Q

mature B cells

A

cells that undergo positive selection, become mature naïve B cells
must co-express IgM and IgD

61
Q

goals of T cell development

A

functional lymphocytes
diverse repertoire
limited self reactivity

62
Q

what are TRECs

A

T Cell receptor excision circles

circular DNA formed by the genomic rearrangement that occurs during V(D)J recombination

63
Q

how are TRECs measured

A

qPCR (reported as number of PRECs per million cells)

64
Q

diagnostic usage of TRECs

A

newborn screening for primary immunodeficiency

thymic output after HSCT

65
Q

double negative thymocytes

A

ab vs yd lineage commitment

pre-TCR expressed

66
Q

double positive thymocytes

A

TCRab, CD4, CD8 expressed

positive and negative selection

67
Q

single positive thymocytes

A

TCRab, and EITHER CD4 or CD8 expressed

68
Q

what is positive selection

A

TCR binds MHC-peptide complexes in the thymus

only cells expressing a TCR that can bind MHC peptide complexes can be positively selected

69
Q

what is negative selection

A

if a cell fails to bind MHC, undergoes apoptosis

if a TCR binds self peptide, it is eliminated to prevent autoreactivity

IBI Test 4 (21 decks)

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