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Mercy CLS 1: Immunology > 9) Lymphs > Flashcards

9) Lymphs Flashcards

1
Q

main 4 characteristics of the immune response

A
  • specificity
  • memory
  • adaptiveness
  • discrimination between self and nonself
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2
Q

parts of clonal selection theory (4)

A
  • lymphs of all specificities exist prior to ag contact
  • each lymph carries Ig/TCR of only one specificity
  • lymphs create progeny with identical specificity
  • self-reactive lymphs are eliminated
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3
Q

marker on pluripotential cell

A

CD34

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4
Q

old way to ID lymphs

A

rosette formation between T cells and sheep RBCs

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5
Q

current methods used to ID lymphs

A

flow cytometry
monoclonal Ab to epitopes

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6
Q

CD stands for…

A

cluster determination

named for Ab that reacts to protein; numbered in order of discovery

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7
Q

developmental stages of B cells

A
  1. pro-B
  2. pre-B
  3. immature B
  4. mature B
  5. B-cell blast/immunoblast
  6. plasma cell/memory cell
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8
Q

most immature committed B-cell

A

pro-B

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9
Q

activity of pro-B

A

starts to rearrange heavy chains
no Ig made

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10
Q

activity of pre-B

A

mu polypeptide forms
(heavy chain of IgM)

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11
Q

activity of immature B-cell

A

light chain genes rearrange
sIgM produced

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12
Q

Ag binding to sIgM on the ——— cell results in deletion, not expansion

A

immature B

in BM, only self antigens are present

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13
Q

activity of mature B-cell

A

expresses IgM, IgD
ready to respond to Ag

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14
Q

antigen dependent B-cell development begins with the ——– stage

A

B-cell blast/immunoblast

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15
Q

formed when Ag triggers IgM+, IgD+ cells to proliferate

A

B-cell blast/immunoblast

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16
Q

——— cells can become ———- cells, but not vice versa

A

memory
plasma

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17
Q

express high level of CD44 (homing)

A

memory B-cells

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18
Q

memory cells found in…

A

secondary lymph tissue

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19
Q

2 ways for B-cells to class switch

A
  • T-cell cytokines
  • T-B surface interactions via CD40 (B) and CD40 ligand (T)
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20
Q

class switching from IgM to…

A

IgG
IgA
IgE

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21
Q

affinity maturation

A

clonal selection of B-cells with mutations for higher affinity Ab to Ag in germinal centers of spleen/lymph nodes

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22
Q

B-cell programmed death occurs in cells with…

A

low affinity for Ag

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23
Q

allows a continuously replenished library of B-cell Ag specificities to exist

A
  • affinity maturation
  • programmed cell death
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24
Q

negative selection of B-cells

A

immature B-cells in contact with self antigens are removed/inactivated

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25
Q

2 reasons to remove/inactivate B-cells

A
  • low affinity for Ag
  • self reactivity
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26
Q

B-cells that do not possess sIg

A
  • pro B
  • plasma
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27
Q

allow us to ID B-cells

A

sIg

28
Q

Ig noncovalently bound to sIg, and found in all stages of B-cells

A

Ig𝛼
Igβ

29
Q

function of Ig𝛼, Igβ

A

linked to kinases inside B-cell
lead to transcrption of genes and B-cell activation

30
Q

function of CD40 (B-cell)

A

links to CD40 ligand on T-cells to mediate class switching

31
Q

disorder involving mutation of CD40 ligand (missing)

A

human X-linked hyper-IgM syndrome

only make IgM
males

32
Q

first B-cell to express MHCII

A

pre-B

33
Q

function of B7 (CD80 + CD86)

A

costimulatory molecule found on APCs
binds CD28 on T-cells
allows T-cell to be turned on by contact with Ag

34
Q

what if T-cell does not receive B7 costimulation?

A

turned off by contact with Ag

35
Q

poor APCs with low levels of costimulatory molecules

A

mature resting B-cells

36
Q

where is FcR (CD32) found?

A

all mature B-cells

37
Q

function of FcR (CD32)

A

if it binds to the Fc portion of an IgG involved in an Ag-Ab complex – while Ag binds sIg on the same cell – the B-cell is inactivated

(negative feedback)

38
Q

function of CD21 (B-cell)

A
  • receptor for C3d
  • receptor for EBV
39
Q

why do we have T and B lymphs?

A

T: antigens inside cells
B: antigens outside cells

40
Q

T-cells only recognize antigen when it is…

A
  • presented on an APC
  • complexed with MHC
41
Q

general structure of TCR

A
  • disulfide linked
  • 2-polypeptide chain (𝛼β or 𝛾𝜹)
  • globulin structure
  • short cytoplasmic tail
42
Q

function of CD3

A

noncovalently associated with the TCR to form the TCR complex

linked to a kinase inside the cell, which leads to gene transcription when TCR binds Ag

43
Q

CD3 structure

A
  • 3 polypeptides (gamma, delta, epsilon)
  • associated with 2 zeta chains (or zeta + eta)
  • found on all T-cells
44
Q

totally intracellular proteins on T-cell

A

2 zeta chains associated with CD3

45
Q

composition of TCR complex

A
  • TCR
  • CD3
  • 2 zeta chains (or zeta + eta)
46
Q

accessory/coreceptor molecules noncovalently linked to TCR

A

CD4 and CD8

47
Q

express CD4 and CD8

A

immature T-cells

48
Q

𝛾𝜹 T-cells mostly express CD—

A

CD8

49
Q

3 functions of CD4/CD8

A
  • adhesion molecules; tighten binding of T-cell to APC (on constant portion of MHC)
  • signal trasducer, phosphorylated when TCR binds Ag
  • CD4 binds HIV
50
Q

possible functions of 𝛾𝜹 T-cells

A

defense against common bacterial antigens and malaria

51
Q

self-MHC restriction

A

only able to bind to self MHC

52
Q

steps in T-cell maturation in thymus

A
  • precursors enter thymus
  • TCR genes rearranged (pre-T)
  • 𝛾𝜹 cells separate from 𝛼β cells
  • thymocytes (T-cells) move from cortex to medulla
  • most mature T-cells enter circulation
53
Q

selection process steps for T-cells

A
  1. positive selection
  2. negative selection
  3. cells become either CD4+ or CD8+
54
Q

T-cell positive selection

A

cells must bind with a certain critical affinity for epithelials’ MHC

cells that survive are “educated”

55
Q

MHC restriction

A

T-cells only respond to type of MHC to which they bound with critical affinity in thymus (pos selection)

56
Q

T-cell negative selection

A

cells interact with interdigitating dendritic cells at cortico-medullary junction, and those reacting with self Ag are removed/inactivated

57
Q

dendritic cells in thymus are involved with…

A

T-cell negative selection

58
Q

—–% of developing T-cells apoptose

A

90

59
Q

reasons for T-cell apoptosis

A
  • TCR genes fail to rearrange successfully
  • precursor not positively selected for
  • cell negatively selected against
60
Q

function of CD28

A

binds to B7 on APC

crucial for IL-2 generation

61
Q

function of CTLA-4

A
  • expressed on activated T-cells
  • binds B7 on APC
  • negative signal; inhibits IL-2 production
62
Q

function of CD2

A
  • T-cells
  • binds LFA-3 (CD58) found on many cells, enhancing binding
63
Q

function of LFA-1

A

binds ICAM-1 (CD54), enhancing binding

64
Q

lymphocyte trafficking

A

“homing” of lymphs to areas where they can interact with Ag

65
Q

where do different lymphs home to?

A
  • naive cells: peripheral nodes
  • activated and memory cells: skin and mucosa
66
Q

function of L-selectin (CD62L)

A
  • homing receptor on T-cell, especially naive
  • homes to peripheral nodes
67
Q

downregulated after T-cell is activated so that it can home to skin, mucosa

A

L-selectin

Mercy CLS 1: Immunology (19 decks)

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