b cell activation Flashcards

1
Q

what is first ig produced in immune response ?

A

igM

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2
Q

what is most abundant Ig in the blood, lymph and tissues?

A

igG

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3
Q

The _____________ is mediated by B-2 B cells binding to TD antigens.

A

T-dependent response

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4
Q

_____________ express _____________ concentrations of transcription factors known to be important in the maintenance of the cellular resting state (quiescence); they are therefore more effectively “poised” to enter the cell cycle.

A

memory B cells; lower

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5
Q

affinity

A

strength of binding of 1 Fab region and the antigen; usually high for bi-valent ig

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6
Q

avidity

A

total affinity of 1 antibody

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7
Q

where does SHM occurs?

A

Dark zone

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8
Q

what regulates class switch recombination? this causes a change in _____

A

Cytokines released by T-cells. Change in isotype produced by B cell.

Class switch recombination (CSR) is instigated by activation-induced cytidine deaminase (AID), which converts cytosines in S regions to uracils. The uracils are subsequently removed by two DNA repair pathways, resulting in mutations, single-strand DNA breaks, and the double-strand breaks required for CSR.

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9
Q

igM is a _____ where each monomeric unit is joined by _______

A

pentamer, disulfide bonds

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10
Q

igM is found in _____ and its function is to ? (Theres 3 mentionned)

A

blood
most efficient ig for activating complement system
ag agglutination
natural antibodies
low affinity since it doesnt need class switch recombination to form

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11
Q

igG has the ______ half life and has _____ subclasses
also is important in what function?

A

longest, four
agglutination (neutrilizes toxinx, immobilizes bacteria, neutralizes viruses)
opsonization
ADCC
Activates complement
Produced in memeory response

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12
Q

what Ig is able to cross the placenta ?

A

igG is passed to newborns via colostrum

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13
Q

what ig is produced in memory response ?

A

igG

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14
Q

what Ig is major in secretions (mucus, saliva, treas, milk)?

A

igA

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15
Q

igA exists as a ______ in secretions and ______ in serum

A

dimer; monomer

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16
Q

igA has ______ subclasses and is important asa primary defense against :

A

two
local respiratory or gastro-intestinal infections

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17
Q

what ig functions in phacocytosis, agglutination, prevents attachement to epithelial surfaces , ACDCC and degranulation?

A

igA

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18
Q

activated B-cells are called:

A

centroblast

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19
Q

proliferating B cells are called

A

centrocytes

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20
Q

of all ig’s, _____ has the shortest half life and is in lowest conc. in the serum

A

igE

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21
Q

what ig plays an important role in protection against parasites, and has an FC region with high affinity to receptors on mast cells and basophils ( allergen)?

A

igE

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22
Q

what ig is found in upper respiratory tract secretions?

A

igD

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23
Q

what two ig binds to mast cells and basophils?

A

igD and IgE

24
Q

what ig’s are coexpressed on the surface of mature, naive B cells?

A

igM and IgD where igD>igM

25
Q

upon binding of antigen, this ig causes increase release in antimicorbial peptides and cytokines

A

igD

26
Q

when igE + allergen complex bind to the Fc receptor specific for igE on a mast cell, _______ causes the release of granule contents such as _______ that mediate allergic reactions

A

degranulation;histamine

27
Q

what reactions involve Fc receptors binding to Fc domains of Abs?

A

transcytosis,
ADCC,
Opsonization and phagocytosis, activation of complement. degranulation

28
Q

in class switch recombination, what makes double-strand breaks in the switch (S) region?

A

AID (activation induced deaminase)

29
Q

differential RNA processing determines whether igM or igD is expressed since

A

cells cannot switch from igM and igD since there is no switch after cdelta

30
Q

igM is produced since

A

C mu is the first after VDJ

31
Q

a cell that can make igM can also make

A

igD

32
Q

in a naive B cell the membrane ig include

A

igM and igD

33
Q

compared to memory cells, naive B cells have a lag time of ______ and a time of peak response of

A

4-7 days
7-10 days

34
Q

compared to naive B cells, memory B cells have a lag time of ______ and a time of peak response of ______

A

1-3 days
3-5 days

35
Q

in a memory B cell what igG predominates?

A

igG

36
Q

naive B cells have a _____ antibody affinity while memory B cells have a _____ antibody affinity

A

low;high

37
Q

compared to memory b cells, naive b cells life span is ______ lived

A

short (days to weeks) while memory is up to the life span of animal host

38
Q

The secondary response to antigen is drastically higher for what ig?

A

igG

39
Q

T-dependent antigens produce

A

memory B cells

40
Q

membrane ig of memory b cells

A

igM, IgG, igA or igE

41
Q

anatomical circulation of naive B cells is ________ and memory B cells is________

A

spleen, LN, corculation,
circulation throughout the body

42
Q

all proteins are _______ while carbohydrates, lipids and nucleic acids are often not_______

A

immunogenic

43
Q

what are the requirements for immunogenicity?

A
  1. foreignness
  2. high molecular weight
  3. chemical complexity
  4. degradability
44
Q

the more _____ a substance, the ____ immunogenic

A

foreign
more

45
Q

how can a molecule with lower molecular weight become immunogenic?

A

coupling it with a larger carrier compound

46
Q

T cells recognize antigens how?

A

only after they have been processed by APCs

47
Q

how do APCs degrade antigens ?

A

since APCs express major histocompatibility complex class I and II, they enzymatically degrade antigens into antigenic peptides (4-10 aa in length) which bind to MHC for presentation to T cells

48
Q

isotypic determinants

A

different epitotes help us determine ig isotype

49
Q

allotypic determinants

A

same ig antibody isotype from different strains

50
Q

idiotypic determinants

A

same ig isotypes but different CDRs

51
Q

strongest response is from what route of antigen administration?

A

subcantaneous

52
Q

adjuvants

A

substances that enhance immune response against the immunogen when mixed with an immunogen

53
Q

the only adjuvant allowed to be used in humans is

A

aluminum potassium sulfate.

54
Q

injection of rabbit igA against mouse would generate antibodies against?

A

rabbit j chain, rabbit alpha heavy chain

55
Q

how is BCR signalling shut down?

A

CD22 OR FcgammaRIIB which comatin ITIMS

56
Q

activation of SHP-1 would have what immediate effect downstream of BCR activation?

A

dephosphorylation of ITAMS

57
Q

how do B-10 B cells act as negative regulators ?

A

secrete il-10 which shuts down inflammatory responses by T cells and APCs