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Immunology - First Aid > Cells of Immunity > Flashcards

Cells of Immunity Flashcards

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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
Cytotoxic T lymphocytes are CD8+ cells which recognize which MHC class?
MHC I
26
What are the effector mechanisms controlled by Th cells?
Antibody synthesis Macrophage activation CTL killing
27
What is CD4+ T cell first signal?
Recognition of specific antigen complexed to | dendritic cell) MHC II ↔ TCR (CD4+ Th cell
28
What is CD4+ costimulatory signal?
Co-stimulation through binding of | B7 (APC) ↔ CD28
29
What is the pattern of differentiation of helper T cells is determined by?
Antigen (type of pathogen causing infection) Cytokines (produced in response to antigen) Transcription factors (stimulated by cytokines)
30
Th1 cells secrete which cytokines?
IFN-γ IL-2
31
Differentiation of Th1 cells is induced by which cytokines?
IFN-γ IL-12
32
Th1 cells are inhibited by which cytokines?
IL-4 IL-10 IL-13 (from Th2 cells)
33
IL-4 & IL-10 inhibit which type of cells?
Th1 cells
34
IFN-γ & IL-12 cause differentiation if which cells?
Th1 cells
35
Th2 cells secrete which cytokines?
IL-4 IL-5 IL-6 IL-10 IL-13
36
Differentiation of Th2 cells is induced by which cytokines?
IL-2 IL-4
37
Th2 cells are inhibited by which cytokines?
IFN-γ | from Th1 cell
38
Intracellular infections promote differentiation of which type of cells?
Th1 cells
39
Functions of Th1 cells
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
Functions of Th2 cells
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
Functions of Th17 cells
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
Functions of Th reg cell
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
What is IPEX syndrome?
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
Deficiency of FoxP3 causes which disorder?
IPEX syndrome Immune dysregulation Polyendocrinopathy Enteropathy X-linked syndrome
45
What is antigen presentation?
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
What signals are required for T cell activation?
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
What is the first signal for T cell activation?
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
What is anergy?
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
Steps in B cells activation
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
Thymus independent B cell activation
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
Thymus dependent B cell activation
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
CD40 ↔ CD40L ligand binding is part of which cell activation?
B cell activation (thymus (T helper cell) dependent)
53
What is co-stimulatory signal of primary T cell activation? Why is it necessary?
APC (CD80/86) B7 ↔ CD28 (naive T cell) Proliferation & survival
54
Which cells determine Ig class isotype switching?
T helper cells
55
What is the principal immunoglobulin of the primary immune response when antigen is first encountered?
IgM
56
IL-4 & IL-13 induce class switching to which Ig?
IgE
57
IL-5 & TGF-β induce class switching to which Ig?
IgA
58
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?
Negative selection
59
APS1 Autoimmune polyendocrinopathy syndrome type 1 features?
CHAR Chronic mucocutaneous candidiasis Hypoparathyroidism Adrenal insufficiency Recurrent Candida infections
60
Autoimmune polyendocrine syndrome-1 is a failure of which part of T cell differentiation?
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
IL-10 & IL-35 & TGF-β are secreted by which T cells? Function?
Th reg cell - anti-inflammatory - ↓CD4 - ↓CD8
62
Th17 secrete which cytokines?
IL-17 IL-21 IL-22
63
Treg cells secrete which cytokines?
TGF-β IL-10 IL-35
64
Th17 cells are inhibited by which cytokines?
IFN-γ IL-4
65
Treg cells are inhibited by which cytokines?
IL-6
66
IL-2 & IL-4 cause the differentiation & proliferation of which T cells?
Th2 cells
67
What happens if APC B7 does not bind to CD28 (on the naïve T cell) in presence of antigen? What is this called?
No T cell activation (failure of costimulation signal) Anergy
68
What is the adaptive immunity in which B lymphocytes produce antibodies? Where are these antibodies present?
Humoral immunity (humoral) circulate in blood as soluble protein
69
Which type of immunity is mediated by T cytotoxic and T helper cells?
Cell-mediated immunity
70
Which immunity is primary defense against extracellular pathogens and/or their toxins? Which cells provide it ? Give some examples of extracellular threats?
Humoral immunity (B cells) Staphylococcus aureus Streptococcus pyogenes Pseudomonas aeruginosa Escherichia coli
71
Which immunity is primary defense against intracellular microbes and tumors? Which cells provide it? Some classical examples of intracellular pathogens?
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
Immunity involving BCR receptors? What are the accessory receptors in this type of immunity?
Humoral immunity Igα & Igβ (signal transducer protein complex by which Ig is attached to B cell) CD40 CD21 Fc receptors
73
Immunity involving TCR receptors? What are the accessory receptors in this type of immunity?
Cell-mediated immunity CD2, CD3, CD4 CD8 CD28 Integrins
74
What molecules are responsible for transplant rejection?
MHC Class I and Class II molecules
75
On what types of cells are Class I MHC molecules expressed?
All nucleated cells
76
What are B cell receptors in their secreted, soluble form called?
Immunoglobulins (Ig) or antibodies
77
What components of an antibody bind antigen?
Fab region
78
Which type of immunity protects against cancers?
Cell-mediated immunity | Humoral immunity cannot eliminate tumor cells & transplants therefore cannot develop immunity
79
Which type of hypersensitivity can cell-mediated immunity cause?
Type IV hypersensitivity reaction (DTH)
80
A delayed-type hypersensitivity reaction to transplant is caused by which type of immunity response?
Cell-mediated immunity

Immunology - First Aid (15 decks)

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