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USMLE Step 1 > Immunology > Flashcards

Immunology Flashcards

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USMLE® Step 1 flashcards
1
Q

Mature T-lymphocytes have these cellular markers

A

CD3: signal transduction T cells
CD4, CD40L: T-helper lymphocyte marker
CD5, CD8: T-cytotoxic lymphocyte marker
CD4, CD25: Regulatory T cells

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2
Q

All leukocyte groups have this cellular marker

A

CD45

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3
Q

Neutrophils have this cellular marker

A

CD15

also Reed-Sternberg Cells in Hodgkins

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4
Q

NK Cells have these cellular markers

A

CD16 (binds Fc of IgG), CD56 (unique marker for NK)

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5
Q

Macrophages and epithelial cells have these cellular markers

A

CD14: endotoxin receptor

Macrophages become multinucleated giant cells

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6
Q

B-lymphocytes have this cellular marker

A

CD19
CD20: signal transduction B cells
CD21 (EBV receptor)

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7
Q

CD19 cells are completely missing in this disease

A

Bruton agammaglobulinemia
(no peripheral immature and mature B cells, low IgG, IgM, IgA)
–> increased susceptibility to encapsulated pyogenic bacteria like H. influenzae, Strep pneumo, Pseudomonas

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8
Q

Triggers neutrophils to enter site of infection, induces phagocytosis in neutrophils

A

IL-8

Released by macrophages, endothelial cells

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9
Q

Stimulates growth and proliferation of stem cells in bone marrow

A

IL-3

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10
Q

Anti-inflammatory cytokines

A

IL-10 –> Limits the production of pro-inflammatory cytokines gamma-interferon, IL-2, IL-3, TNF-a

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11
Q

Triggers vasoconstriction, vascular permeability, bronchospasm

A

Leukotriene C4, D4, E4

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12
Q

Stimulates neutrophil migration to site of inflammation

A

Leukotriene B4, IL-8

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13
Q

Mediate vasodialtion, vascular permeability

A

PGI2, PGD2, PGE2 (also fever)

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14
Q

Attracts and activates neutrophils

A

LTB4 (C4, D4, E4)

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15
Q

Things that can activate mast cells

A

tissue trauma; complement proteins c3a, c5a; cross-linking of IgE by Antigen

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16
Q

Activation of Classical complement pathway

A

IgG, IgM bound to Ag –> binds C1

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17
Q

Activation of Alternative complement pathway

A

Microbial products directly activate complement

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18
Q

Form membrane attack complex

A

C6-C9 –> lyse microbe by creating hole in cell membrane

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19
Q

Secreted by Weibel-Palade bodies

A

P-selectin (rolling or neutrophils)

vonWillebrand factor

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20
Q

Role of bradykinin

A

mediates vasodilation, increased vascular permeability, pain (with PGE2)

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21
Q

Mediators of fever

A

IL-1, TNF, PGE2 (raises temperature set point)

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22
Q

Steps + Key mediators in Neutrophil arrival and function

A

1) Margination (vasodilation slows blood)
2) Rolling (P/E selectin bind sialyl Lewis X)
3) Adhesion (ICAM/VCAM upreg by TNF/IL-1)
(Leukocyte Adhesion Def d/t CD18 defect)
4) Transmigration/Chemotaxis (IL-8, C5a, LtB4)
5) Phagocytosis (enhanced by opsonins IgG/C3b)
(Chediak-Higashi microtubule trafficking defect)
6) O2 dependent killing (HOCl actually kills)
(CGD oxidase defect, MPO deficiency no HOCl)
7) Resolution (neutrophils become pus, disappear)

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23
Q

Present in late inflammation

A

Macrophages

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24
Q

Antiinflammatory cytokines produced by macrophages

A

IL-10, TGF-B

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25
Q

Present in chronic inflammation

A

lymphocytes, plasma cells

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26
Q

Activation required for CD4 helper T cells

A

Extracellular Ag: MHC II –> APC
B7:CD28 –> 2nd signal
TH1 secretes IFNy –> activate macro, B class switching, inhibitory to TH2
TH2 secretes IL-4, IL-5, IL-13 –> class switching, eosinophil chemotaxis and activation

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27
Q

Activation required for CD8 cytotoxic T cells

A

Intracellular Ag: MHC I –> expressed on all nucleated cells and platelets
IL-2 from CD4/TH1 –> 2nd signal

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28
Q

Function of FAS (CD95)

A

Cytotoxic T cells express FasL, which binds FAS and activates Apoptosis (extrinsic pathway)

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29
Q

B cell activation

A

Immature B cells express IgM/IgD

Antigen binding results in maturation –> plasma cells with secretion

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30
Q

Epitheliod histiocytes are characteristic of

A

Granuloma

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31
Q

Main antibody in secondary response to antigen

A

IgG

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32
Q

Antibody that prevents attachment of bacteria/viruses to mucous membranes

A

IgA

33
Q

Immediate antibody response to antigen

A

IgM

34
Q

Found on surface of B cells and in serum

A

IgD

35
Q

Cross-link when exposed to allergen

A

IgE

36
Q

Most abundant antibody isotype in serum

A

IgG

37
Q

Most produced antibody overall

A

IgA (produced in GI track)

38
Q

Antibody that is a monomer on B cells, in pentamer form when secretedSti

A

IgM

39
Q

Mediate isotype switching

A

cytokines, CD40L

40
Q

Secreted in tears, saliva, mucus, breast milk

A

IgA

41
Q

Mediates immediate hypersensitivity through release of histamine and other inflammatory mediators

A

IgE

42
Q

Lowest antibody concentration in serum

A

IgE

43
Q

Crosses the placenta for passive immunity

A

IgG

44
Q

Neutralizes bacterial toxins, viruses; Opsonizes bacteria

A

IgG

45
Q

Stimulates acute phase proteins, causes fever

A

IL-6

46
Q

Major chemotactic factor for neutrophils

A

IL-8, leukotriene B4

47
Q

Causes cachexia in malignancy

A

TNF-a (secreted by NK, Macrophages)

48
Q

Induces differentiation of T cells into TH1 cells, activates NK cells

A

IL-12

–> IL-12 receptor deficiency: mycobacterial + fungal infections

49
Q

Secreted by ALL T cells

A

IL-2: stimulates proliferation of all other lymphocytes

IL-3: supports bone marrow stem cells, like GM-CSF

50
Q

Interferon-y function

A

Secreted by Th1/NK cells re: IL-12
Stimulates macrophages to kill phagocytosed pathogens
Activates NK for virus-infected-cell killing
Increases MHC expression/antigen presentation

51
Q

Secreted by Th2 cells

A 
IL-4: induces diff into Th2, promotes B growth, enhances class switching to IgE/IgG
IL-5: Promotes diff of B cells, enhance class switching to IgA, stim eosinophils
IL-10: modulate inflammatory response
52
Q

These inhibit Th1 cells

A

IL-4, IL-10

53
Q

Function of IFN-a, IFN-B

A

Synthesized by virally infected cells, these act on local uninfected cells, prime them for viral defense –> apoptosis and disruption of viral replication

54
Q

Antibodies involved in Type II hypersensitivity

A

IgM, IgG –> bind to fixed antigen –> cellular destruction via opsonization, complement or antibody-mediated

55
Q

Coombs’ tests are examples of…

A

Type II hypersensitivity

56
Q

Detects antibodies that have adhered to patient’s RBCs (eg test Rh+ infant or Rh- mother)

A

DIRECT Coombs’ test

–> Antibodies are directly on RBCs

57
Q

Detects antibodies in serum that can adhere to other RBCs (eg test Rh- woman for Rh+ antibodies present)

A

INDIRECT Coombs’ test

–> Antibodies are free

58
Q

Characteristic of Type III hypersensitivity

A

Antigen-Antibody-Complement stuck together –> Immune complex activates complement –> attracts neutrophils –> release lysosomal enzymes

59
Q

Examples of Type III hypersensitivity

A

Serum sickness (abs to foreign proteins/drugs); Arthus reaction (local injection of antigen –> edema, necrosis); SLE, Rheumatoid arthritis, post-strept glomerulonephritis, polyarteritis nodosa, Henoch-Schonlein purpura

60
Q

Type IV Hypersensitivity is

A

Delayed - Tcell mediated
T-cells encounter Ag –> release cytokines
No antibody involved

T-cells, Transplant, TB skin test, Touching (contact derm)

61
Q

Type I hypersensitivity is

A

Immediate
Free antigen cross-links IgE –> immediate release of vasoactive amines
Due to preformed antibody
Delayed response due to arachidonic acid metabolites (leukotrienes)

62
Q

Calcineurin inhibitors

A

Cyclosporine - prevents IL-2 transcription by binding cyclophilin
Tacrolimus - prevents IL-2 transcription by binding FK506

Prevent IL-2 transcription –> Prevent T cell activation
BOTH HIGHLY NEPHROTOXIC

63
Q

mTOR inhibitor that prevents response/signal transduction to IL-2

A

Sirolimus/Rapamycin - binds FKBP, blocks T-cell activation and B-cell differentiation

Causes anemia, thrombocytopenia, leukopenia, peripheral edema

Use for kidney transplant since not nephrotoxic

64
Q

Monoclonal antibodies that block IL-2R

A

Daclizumab, Basiliximab

65
Q

Antimetabolite precursor of 6-mercaptopurine

A

Azathioprine

Causes leukopenia, anemia, thrombocytopenia

66
Q

Inhibit NF-KB, suppress B and T cell function by decreasing transcription of cytokines

A

Glucocorticoids

67
Q

Rituximab target and clinical use

A

CD20, B-cell non-Hodgkin lymphoma, CLL, RA, ITP

68
Q

Trastuzumab target and clinical use

A

HER2/neu, breast cancer

69
Q

Adalimumab, Infliximab target and clinical use

A

TNF-a, IBD, RA

70
Q

Denosumab target and clinical use

A

RANK-L, osteoporosis, inhibits osteoclast maturation mimicking osteoprotegerin

71
Q

Palivizumab target and clinical use

A

RSV F protein, prophylaxis in high-risk

72
Q

Abciximab target and clinical use

A

platelet glycoproteins IIb/IIIa, prevention in PCI

73
Q

Omalizumab target and clinical use

A

IgE, allergic asthma last line treatment, prevents binding

74
Q

Hematopoietic stem cells have this marker

A

CD34

75
Q

Two extrinsic pathway apoptosis mechanism

A

FAS ligand (CD95) and TNF1 receptor

76
Q

Intrinsic apoptosis pathway mechanism

A

Mitochondria become more permeable –>
Anti-apoptotic BCL2 and Bclx become Pro-apoptotic Bak, Bax and Bim –> mitochrondria leaks caspase-activating cytochrome c

77
Q

CD55 and CD59 are associated with

A

Paroxysmal Nocturnal Hemoglobinuria

78
Q

Cells present in sarcoidosis

A

CD4+

USMLE Step 1 (5 decks)

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