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Immunology - First Aid > Cells of Immunity > Flashcards

Cells of Immunity Flashcards

1
Q

NK natural killer cells are a member of which type of immunity?

A

Innate immunity

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2
Q

NK natural killer cells target which type of cells?

A

Virally infected cells

Tumor cells

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3
Q

What mechanisms do NK natural killer cells use to induce apoptosis?

A

Perforin

Granzymes

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4
Q

NK natural killer cells activity is increased in the presence of which cytokines?

A

IL-2

IL-12

IFN-α

IFN-β

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5
Q

CD16 & CD56 can clinically enumerate which type of cells?

A

NK natural killer cells

CD16: Opsonization ADCC
CD56: Cell adhesion

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6
Q

How are NK natural killer cells activated?

A

When exposed to nonspecific activation signal on target cell

and/or

An absence of MHC I on target cell surface

and/or

ADCC antibody-dependent cell-mediated cytotoxicity (CD16 binds Fc region of bound Ig → activating NK cells)

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7
Q

Perforins & granzymes are part of which lymphocytes mechanism for killing?

A

NK natural killer cells

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8
Q

B cells are a member of which type of immunity?

A

Humoral immunity (adaptive)

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9
Q

T cells mediate which type of immunity?

A

Cell-mediated immunity (adaptive)

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10
Q

Recognizing antigen and undergoing somatic hypermutation to optimize antigen specificity is a function of which cells?

A

B cells

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11
Q

What are major function of B cells?

A

Recognize Ag
- undergo somatic hypermutation to optimize Ag specificity

Produce Antibodies
- differentiate into plasma cells to secrete specific Igs

Maintain immunologic memory
- memory B cells persist & accelerate future response to Ag

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12
Q

T cells are a part of which type of hypersensitivity?

A

Delayed cell-mediated hypersensitivity (type IV)

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13
Q

What are major function of T cells?

A

CD4+ T cells

  • help B cells make antibodies
  • produce cytokines to recruit phagocytes
  • activate other leukocytes

CD8+ T cells

  • directly kill virus-infected cells
  • kill neoplastic cells
  • kill donor graft cells (apoptosis)
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14
Q

Where does the positive selection of T cells take place?

A

Thymic cortex

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15
Q

Where does the negative selection of T cells take place?

A

Thymic medulla

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16
Q

Which cells are the APC (antigen presenting cells)?

A

B cells

Dendritic cells

Macrophages

Langerhans cells

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17
Q

What is T cell positive selection?

A

T cells expressing TCRs capable of binding self-MHC with low affinity on cortical epithelial cells → survive & mature

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18
Q

What is failure of positive selection?

A

T cells that fail to recognize self-MHC (self-antigen) at all will not survive & mature

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19
Q

What is T cell negative selection?

A

T cells that bind too strongly (high affinity) to self-MHC and self-peptide undergo apoptosis

(b/c these cells have potential to cause autoimmune disease)

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20
Q

What is the function of AIRE (autoimmune regulator)?

A

Tissue-restricted self-antigens are expressed in thymus & enhances clonal deletion of auto-reactive thymocytes

(It exposes T cells to normal, healthy proteins from all parts of the body, and T cells cannot bind Ag without MHC but it makes them do it anyway and if they react to those proteins, they are destroyed)

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21
Q

What AIRE (autoimmune regulator) deficiency lead to?

A

APS1
Autoimmune polyendocrinopathy syndrome type 1

APECED
Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy

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22
Q

CD4+ cells that recognize MHC II will eventually mature into which cells?

A

Helper T cells (Th)

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23
Q

CD8+ cells that recognize MHC I will eventually mature into which cells?

A

Cytotoxic T Lymphocytes (CTLs)

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24
Q

Helper T cells are the CD4+ cells which recognize which class of MHC?

A

MHC II

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25
Q

Cytotoxic T lymphocytes are CD8+ cells which recognize which MHC class?

A

MHC I

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26
Q

What are the effector mechanisms controlled by Th cells?

A

Antibody synthesis

Macrophage activation

CTL killing

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27
Q

What is CD4+ T cell first signal?

A

Recognition of specific antigen complexed to

dendritic cell) MHC II ↔ TCR (CD4+ Th cell

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28
Q

What is CD4+ costimulatory signal?

A

Co-stimulation through binding of

B7 (APC) ↔ CD28

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29
Q

What is the pattern of differentiation of helper T cells is determined by?

A

Antigen (type of pathogen causing infection)

Cytokines (produced in response to antigen)

Transcription factors (stimulated by cytokines)

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30
Q

Th1 cells secrete which cytokines?

A

IFN-γ

IL-2

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31
Q

Differentiation of Th1 cells is induced by which cytokines?

A

IFN-γ

IL-12

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32
Q

Th1 cells are inhibited by which cytokines?

A

IL-4

IL-10

IL-13

(from Th2 cells)

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33
Q

IL-4 & IL-10 inhibit which type of cells?

A

Th1 cells

34
Q

IFN-γ & IL-12 cause differentiation if which cells?

A

Th1 cells

35
Q

Th2 cells secrete which cytokines?

A

IL-4

IL-5

IL-6

IL-10

IL-13

36
Q

Differentiation of Th2 cells is induced by which cytokines?

A

IL-2

IL-4

37
Q

Th2 cells are inhibited by which cytokines?

A

IFN-γ

from Th1 cell

38
Q

Intracellular infections promote differentiation of which type of cells?

A

Th1 cells

39
Q

Functions of Th1 cells

A

Activate macrophages & cytotoxic T cells

Intracellular infection response
(transcription factor T-bet) → secrete

IFN-γ

  • ↑Th1 response
  • ↓Th2 response
  • activate classical macrophage
  • isotype switching to IgG

&

IL-2
- ↑ proliferation & activity of Ag-primed Th & CTLs

40
Q

Functions of Th2 cells

A

Parasitic infection response (transcription factor GATA3) → activate eosinophils, IgE

IL-4
- ↑Th2 response

IL-4 & IL-13

  • Isotype switching to IgE
  • activate alternative macrophage

IL-5
- Eosinophil activation & maturation

TGF-β
- Isotype switching to IgA

IL-4 & IL-10
- ↓Th2 response

41
Q

Functions of Th17 cells

A

Induce neutrophilic inflammation

-Extracellular bacterial & fungal infection response (transcription factor RORγT) → secrete

  • IL-17
  • activates tissue cells & leukocytes to secrete inflammatory cytokines → recruitment of neutrophils
  • IL-17/ IL-21/ IL-22
  • act on epithelial cells to secrete antimicrobials
  • improve endothelial barrier function
42
Q

Functions of Th reg cell

A

Maintain tolerance/ regulate (inhibit) Th1 function (transcription factor FoxP3 & CD3, CD4, CD25) & prevent autoimmunity

IL-10/ IL-35/ TGF-β

  • anti-inflammatory
  • ↓CD4
  • ↓CD8
43
Q

What is IPEX syndrome?

A

Immune dysregulation
Polyendocrinopathy
Enteropathy
X-linked syndrome

Genetic deficiency FoxP3 → autoimmunity

  • enteropathy
  • endocrinopathy
  • nail dystrophy
  • dermatitis
  • derma issues
  • associated with DM in male infants
44
Q

Deficiency of FoxP3 causes which disorder?

A

IPEX syndrome

Immune dysregulation
Polyendocrinopathy
Enteropathy
X-linked syndrome

45
Q

What is antigen presentation?

A

Needed for T cell activation

Dendritic cell (specialized APC) sample antigen → process antigen → migrate to draining lymph node to look for naïve T lymphocyte to present antigen

46
Q

What signals are required for T cell activation?

A

Primary T cell activation involves the integration of three distinct signals after antigen recognition:

(1) T-cell activation (first signal)
MHC II ↔ TCR on CD4

or

MHC I ↔ CD8+ T cytotoxic cells

(2) Proliferation & survival (costimulatory signal)
APC (CD80/86) B7 ↔ CD28 (naive T cell)

(3) Differentiation (cytokine- mediated)
T helper cell activate & produce
IL-4/ IL-6/ IL-12/ TGF-β

T cytotoxic cells activate & kill virus-infected cell

47
Q

What is the first signal for T cell activation?

A

Recognition of specific antigen complexed to
(dendritic cell) MHC II ↔ TCR (CD4+ Th cell)

or

endogenous or cross-presented antigen is presented on
MHC I ↔ CD8+ T cytotoxic cells

48
Q

What is anergy?

A

Anergy is a state during which a cell cannot become activated by exposure to its antigen.

T and B cells become anergic when exposed to their antigen without costimulatory signal
[failure of signal 2:
APC (CD80/86) B7 ↔ CD28 (naive T cell)]

Another mechanism of self-tolerance.

49
Q

Steps in B cells activation

A

First signal

  • mature naïve B lymphocytes circulating and aggregating in follicular areas of 2° lymphoid organs (lymph nodes & spleen)
  • antigen bind and cross-link idiotype of the immunoglobulin
50
Q

Thymus independent B cell activation

A

TI-Antigen activated B cells

  • Thymus independent
  • Macromolecules (lipids, polysaccharides, lipopolysaccharides) (gram -ive bacteria) lack peptide component
  • directly stimulate B cell (don’t require T helper cell)
  • weaker response than TD (weak immunogenic)
  • IgM mostly
  • no memory

-vaccines often require boosters & adjuvants (pneumococcal polysaccharide vaccine)

51
Q

Thymus dependent B cell activation

A

TD-Antigen activated B cells

  • thymus dependent
  • contain protein component (diptheria vaccine)

(1) T helper cell activation (1st/2nd/3rd signals)
(2) B cell receptor-mediated endocytosis
(3) antigen presented on MHC II ↔ TCR (T helper cells)
(4) B cell CD40 ↔ CD40L ligand (T helper cell)
(5) T helper cell secrete cytokines → Ig class switching of B cell → B cell activates → class switching → affinity maturation → antibody maturation

52
Q

CD40 ↔ CD40L ligand binding is part of which cell activation?

A

B cell activation (thymus (T helper cell) dependent)

53
Q

What is co-stimulatory signal of primary T cell activation?

Why is it necessary?

A

APC (CD80/86) B7 ↔ CD28 (naive T cell)

Proliferation & survival

54
Q

Which cells determine Ig class isotype switching?

A

T helper cells

55
Q

What is the principal immunoglobulin of the primary immune response when antigen is first encountered?

A

IgM

56
Q

IL-4 & IL-13 induce class switching to which Ig?

A

IgE

57
Q

IL-5 & TGF-β induce class switching to which Ig?

A

IgA

58
Q

The process in which T cells that bind too strongly (high affinity) to self-MHC and self-peptide undergo apoptosis or become regulatory T cells is called?

A

Negative selection

59
Q

APS1 Autoimmune polyendocrinopathy syndrome type 1 features?

A

CHAR

Chronic mucocutaneous candidiasis

Hypoparathyroidism

Adrenal insufficiency

Recurrent Candida infections

60
Q

Autoimmune polyendocrine syndrome-1 is a failure of which part of T cell differentiation?

A

Negative selection

Tissue-restricted self-antigens are expressed in the thymus due to autoimmune regulator (AIRE)
so T cells expressing TCRs with high affinity for self antigens will not undergo apoptosis

61
Q

IL-10 & IL-35 & TGF-β are secreted by which T cells?

Function?

A

Th reg cell

  • anti-inflammatory
  • ↓CD4
  • ↓CD8
62
Q

Th17 secrete which cytokines?

A

IL-17

IL-21

IL-22

63
Q

Treg cells secrete which cytokines?

A

TGF-β

IL-10

IL-35

64
Q

Th17 cells are inhibited by which cytokines?

A

IFN-γ

IL-4

65
Q

Treg cells are inhibited by which cytokines?

A

IL-6

66
Q

IL-2 & IL-4 cause the differentiation & proliferation of which T cells?

A

Th2 cells

67
Q

What happens if APC B7 does not bind to CD28 (on the naïve T cell) in presence of antigen?

What is this called?

A

No T cell activation (failure of costimulation signal)

Anergy

68
Q

What is the adaptive immunity in which B lymphocytes produce antibodies?

Where are these antibodies present?

A

Humoral immunity

(humoral) circulate in blood as soluble protein

69
Q

Which type of immunity is mediated by T cytotoxic and T helper cells?

A

Cell-mediated immunity

70
Q

Which immunity is primary defense against extracellular pathogens and/or their toxins? Which cells provide it ?

Give some examples of extracellular threats?

A

Humoral immunity
(B cells)

Staphylococcus aureus
Streptococcus pyogenes
Pseudomonas aeruginosa
Escherichia coli

71
Q

Which immunity is primary defense against intracellular microbes and tumors? Which cells provide it?

Some classical examples of intracellular pathogens?

A

Cell-mediated immunity
(T cells)

(viruses, bacteria, parasites, tumor cells)

Brucella abortus (brucellosis)
Listeria monocytogenes (listeriosis)
Chlamydia trachomatis
Coxiella burnetii (Q fever)
Mycobacterium tuberculosis
Salmonella enterica
72
Q

Immunity involving BCR receptors?

What are the accessory receptors in this type of immunity?

A

Humoral immunity

Igα & Igβ
(signal transducer protein complex by which Ig is attached to B cell)

CD40

CD21

Fc receptors

73
Q

Immunity involving TCR receptors?

What are the accessory receptors in this type of immunity?

A

Cell-mediated immunity

CD2, CD3, CD4

CD8

CD28

Integrins

74
Q

What molecules are responsible for transplant rejection?

A

MHC Class I and Class II molecules

75
Q

On what types of cells are Class I MHC molecules expressed?

A

All nucleated cells

76
Q

What are B cell receptors in their secreted, soluble form called?

A

Immunoglobulins (Ig) or antibodies

77
Q

What components of an antibody bind antigen?

A

Fab region

78
Q

Which type of immunity protects against cancers?

A

Cell-mediated immunity

Humoral immunity cannot eliminate tumor cells & transplants therefore cannot develop immunity

79
Q

Which type of hypersensitivity can cell-mediated immunity cause?

A

Type IV hypersensitivity reaction (DTH)

80
Q

A delayed-type hypersensitivity reaction to transplant is caused by which type of immunity response?

A

Cell-mediated immunity

Immunology - First Aid (15 decks)

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