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Undeleted > B cells > Flashcards

B cells Flashcards

1
Q

what is key to clonal selection

A

each lymphocyte has receptors to only a single antigen

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2
Q

know clonal selection maps

A

see notes

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3
Q

main B cell funct.

A

make antibodies to mark things for detruction

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4
Q

what are steps to make an antibody

A
  1. mature B cell bind with antigen
  2. makes plasma cells
  3. creates antibodies to that path.
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5
Q

what is basic structure of antibody

A 
1 heavy chain and 2 light chains
variable region (Fab) and constant region (Fc)
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6
Q

4 functions of antibodies

A
  1. neutralization of toxins/bact
  2. opsinization
  3. activation of complement cascade
  4. help activate special cells
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7
Q

how does anti-body neutralize toxin/virus

A

binds to it so it cannot bind to cell receptor and enter the cell

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8
Q

how does antibody opsinize

A

Fab binds to bacteria and Fc binds to phagocytic cell and leads to phag of bact.

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9
Q

how does antibody activate complement cascade

A

classical pathway - C3 activation

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10
Q

what are antibody isotypes

A

different sublasses of anti bodies that have diff. functions and circulate in different areas

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11
Q

what is location and function of IgG

A
  • small and all tissues

- opsinization and complement activation (C1)

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12
Q

what is location and function of IgM

A
  • pentameric structure that is large and can’t leave blood

- binds strongly as first line and can also activate complement

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13
Q

what is location and function of IgA

A
  • in secretions esp resp and intestinal tracts

- poor opsonin and weak complement activator

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14
Q

what is location and function of IgE

A
  • trace amount in serum, most in mast cells under skin

- binding causes mast cells to degranulate leading to sneeze cough - involved in allergic rxns

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15
Q

how do B cells recognize antigen

A

with same imbedded immunoglobin that will become and antibody

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16
Q

what are 2 things B cell dev. must acheive

A
  1. large repetoire of antibodies

2. antibodies that can function in different ways (ISOtypes)

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17
Q

how does B cell gen diversity?

A

through recombining V,D,J in somatic recombination

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18
Q

what is light chain recombination steps

A
  1. germline DNA
  2. recombination
  3. VJ joined DNA
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19
Q

what is heavy chain recombination steps

A
  1. germlineDNA
  2. recombination
  3. DJ joined DNA
  4. recombination
  5. VDJ joined DNA
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20
Q

how does recombination control lymphocyte dev (2)

A
  1. allows progression to next stage

2. prevent further rearrangement allowing single specificity for each cell

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21
Q

where are 2 checkpoints in dev.

A

after heavy and light chain rearrangments

22
Q

what happens if no receptor made?

A

apoptosis

23
Q

where does rearrangment occur

A

bone marrow

24
Q

what is product of rearrangment

A

immature B cell in bone marrow with IgM on surface

25
Q

what is key life event of B cell

A

expression of IgM on surface

26
Q

what is tolerance

A

only those B-cells that do not recognize self antigen are allowed to leave bone marrow

27
Q

where does B-cell go after marrow

A

secondary lymphoid tissues

28
Q

how does Bcell know where to go

A

chemokines

29
Q

where does B cell go in lymph node

A
  1. to T cell area to look for antigen

2. if none move to B cell area in cortex

30
Q

3 requirements for B cell activation

A
  1. cross-linking of surface imunoglobulin by specific antigen
  2. association of Bcell receptor with B cell co-receptor
  3. additional signal from helper T cell
31
Q

what is T-cell help

A
  1. B cell links with T cell with same antigen spec.
  2. linkage causes T cell to release cytokines that activate B cell
  3. B cell become plasma cell
32
Q

what happens when B cell meets correct T cell in node

A
  1. cognate pair travel to medularry cords
  2. undergo clonal expansion
  3. cause primary focus
33
Q

what is primary focus

A

rapid early diff of B cells without T cells to create IgM as initial attack

34
Q

what is secondary focus

A

movement of activated B cells out to form a germinal center

35
Q

what is in germinal center (3)

A
  1. activated B cells
  2. T cells
  3. antigen
36
Q

what occurs in the germinal center

A

rapid B cell prolif. leads to

  1. somatic hypermutation
  2. affinity maturation
37
Q

what is affinity maturation

A

finds B cells that have strong affinity for antigen and brought to T cell for extra reproduciton

38
Q

where does isotype switching occur

A

in the germinal center

39
Q

what is isotype switching

A

original expression of IgM is changed to another type

40
Q

how does isotype switching occur

A

due to recombination within the cluster of C genes

41
Q

what are outcomes of B cells in germinal center (2)

A
  1. become plasma cell via IL-10

2. memory cell via IL-4

42
Q

how to identify and lymphocytic leukemia

A

will all have the same Ig receptor on surface

43
Q

how to identify myleloma (plasma cell)

A

will produce tones of same antibody

44
Q

what antibodies are in the brain and a fetus

A

brain - none

fetus - IgG

45
Q

what does IgA do

A

protects mucosal surface

46
Q

what is IgA mechanism

A
  1. released from basement membrane and when bound is phagocytosed into cell and excreted into the lumen
  2. once in lumen it can help bind bacteria etc. in tract to can’t reporoduce and poo it out
47
Q

what is ADCC

A

antibody dep. cytotoxicity - opsinize so binds with NK cells

48
Q

how does C3b react with RBCs

A
  1. bound C3b binds with CR1 receptor on RBC

2. RBC carries it around until meets macrophage to take it off

49
Q

how does allergy happen

A

mast cell response binds to non-threatening antigens via IgE causing reaction

50
Q

what is anaphylaxis

A

make IgE to protein antigens such as peanuts and mast cell becimes coated
2. future contact leads to massive degranulation

51
Q

what are autoantibodies

A

antibodies that recognize self - loss of tolerance

52
Q

see conclusion slides

A

it will be helpful

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