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USMLE Step 1 > Immunology > Flashcards

Immunology 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
Present in chronic inflammation
lymphocytes, plasma cells
26
Activation required for CD4 helper T cells
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
27
Activation required for CD8 cytotoxic T cells
Intracellular Ag: MHC I --> expressed on all nucleated cells and platelets IL-2 from CD4/TH1 --> 2nd signal
28
Function of FAS (CD95)
Cytotoxic T cells express FasL, which binds FAS and activates Apoptosis (extrinsic pathway)
29
B cell activation
Immature B cells express IgM/IgD | Antigen binding results in maturation --> plasma cells with secretion
30
Epitheliod histiocytes are characteristic of
Granuloma
31
Main antibody in secondary response to antigen
IgG
32
Antibody that prevents attachment of bacteria/viruses to mucous membranes
IgA
33
Immediate antibody response to antigen
IgM
34
Found on surface of B cells and in serum
IgD
35
Cross-link when exposed to allergen
IgE
36
Most abundant antibody isotype in serum
IgG
37
Most produced antibody overall
IgA (produced in GI track)
38
Antibody that is a monomer on B cells, in pentamer form when secretedSti
IgM
39
Mediate isotype switching
cytokines, CD40L
40
Secreted in tears, saliva, mucus, breast milk
IgA
41
Mediates immediate hypersensitivity through release of histamine and other inflammatory mediators
IgE
42
Lowest antibody concentration in serum
IgE
43
Crosses the placenta for passive immunity
IgG
44
Neutralizes bacterial toxins, viruses; Opsonizes bacteria
IgG
45
Stimulates acute phase proteins, causes fever
IL-6
46
Major chemotactic factor for neutrophils
IL-8, leukotriene B4
47
Causes cachexia in malignancy
TNF-a (secreted by NK, Macrophages)
48
Induces differentiation of T cells into TH1 cells, activates NK cells
IL-12 | --> IL-12 receptor deficiency: mycobacterial + fungal infections
49
Secreted by ALL T cells
IL-2: stimulates proliferation of all other lymphocytes | IL-3: supports bone marrow stem cells, like GM-CSF
50
Interferon-y function
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
Secreted by Th2 cells
``` 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
These inhibit Th1 cells
IL-4, IL-10
53
Function of IFN-a, IFN-B
Synthesized by virally infected cells, these act on local uninfected cells, prime them for viral defense --> apoptosis and disruption of viral replication
54
Antibodies involved in Type II hypersensitivity
IgM, IgG --> bind to fixed antigen --> cellular destruction via opsonization, complement or antibody-mediated
55
Coombs' tests are examples of...
Type II hypersensitivity
56
Detects antibodies that have adhered to patient's RBCs (eg test Rh+ infant or Rh- mother)
DIRECT Coombs' test | --> Antibodies are directly on RBCs
57
Detects antibodies in serum that can adhere to other RBCs (eg test Rh- woman for Rh+ antibodies present)
INDIRECT Coombs' test | --> Antibodies are free
58
Characteristic of Type III hypersensitivity
Antigen-Antibody-Complement stuck together --> Immune complex activates complement --> attracts neutrophils --> release lysosomal enzymes
59
Examples of Type III hypersensitivity
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
Type IV Hypersensitivity is
Delayed - Tcell mediated T-cells encounter Ag --> release cytokines No antibody involved T-cells, Transplant, TB skin test, Touching (contact derm)
61
Type I hypersensitivity is
Immediate Free antigen cross-links IgE --> immediate release of vasoactive amines Due to preformed antibody Delayed response due to arachidonic acid metabolites (leukotrienes)
62
Calcineurin inhibitors
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
mTOR inhibitor that prevents response/signal transduction to IL-2
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
Monoclonal antibodies that block IL-2R
Daclizumab, Basiliximab
65
Antimetabolite precursor of 6-mercaptopurine
Azathioprine Causes leukopenia, anemia, thrombocytopenia
66
Inhibit NF-KB, suppress B and T cell function by decreasing transcription of cytokines
Glucocorticoids
67
Rituximab target and clinical use
CD20, B-cell non-Hodgkin lymphoma, CLL, RA, ITP
68
Trastuzumab target and clinical use
HER2/neu, breast cancer
69
Adalimumab, Infliximab target and clinical use
TNF-a, IBD, RA
70
Denosumab target and clinical use
RANK-L, osteoporosis, inhibits osteoclast maturation mimicking osteoprotegerin
71
Palivizumab target and clinical use
RSV F protein, prophylaxis in high-risk
72
Abciximab target and clinical use
platelet glycoproteins IIb/IIIa, prevention in PCI
73
Omalizumab target and clinical use
IgE, allergic asthma last line treatment, prevents binding
74
Hematopoietic stem cells have this marker
CD34
75
Two extrinsic pathway apoptosis mechanism
FAS ligand (CD95) and TNF1 receptor
76
Intrinsic apoptosis pathway mechanism
Mitochondria become more permeable --> Anti-apoptotic BCL2 and Bclx become Pro-apoptotic Bak, Bax and Bim --> mitochrondria leaks caspase-activating cytochrome c
77
CD55 and CD59 are associated with
Paroxysmal Nocturnal Hemoglobinuria
78
Cells present in sarcoidosis
CD4+

USMLE Step 1 (5 decks)

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