Immunology Flashcards

1
Q

What is the definition of a true autoimmune disease?

A

Loss of immune tolerance to your own tissues

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2
Q

What are some immunoprotective properties of skin?

A

Sebum
Low pH
Secretion of enzymes
Periodic desquamation
Normal flora
Dendritic cells
Gamma-delta T cells

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3
Q

What are the inflammatory mediators of the innate immune system?

A

Chemokines and cytokines

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4
Q

Which pathway of the complement system involves the innate immune system?

A

Alternate pathway

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5
Q

Fever is mediated by what pyrogenic cytokines?

A

IL-1
IL-6
TNF-alpha

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6
Q

What is central tolerance and when is it acquired?

A
  • Inability to pathologically respond to self
  • Acquired during B and T cell ontogeny
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7
Q

What is peripheral tolerance?

A

Inability of mature T and B cells to pathologically respond to self

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8
Q

What is an alloantigen?

A

Tissue from genetically dissimilar individuals of the SAME species

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9
Q

What is a xenoantigen?

A

Tissue from genetically dissimilar individuals of a DIFFERENT species

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10
Q

What is an autoantigen?

A

A component of the host’s body that becomes antigenic

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11
Q

What is a superantigen?

A

Bacterial or retrovial products that bind directly to MHC II outside the antigen binding groove

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12
Q

Superantigens bind the T cell receptor outside the conventional binding site with specificity for what chain?

A

Beta chain

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13
Q

What is an epitope?

A

The part of an antigen that is capable of inducing an immune response

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14
Q

What is a hapten?

A

Small chemical groups that are generally not antigenic but can induce an immune response by binding to a larger protein molecule (carrier protein)

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15
Q

What immunoglobulin is the major serum immunoglobulin?

A

IgG

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16
Q

Where is IgG found?

A

Blood and ECF

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17
Q

What are IgG’s two main functions?

A

Opsonization
Virus neutralization

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18
Q

What is the first immunoglobulin produced during humoral responses?

A

IgM

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19
Q

How many immunoglobulin units does IgM have? This translates to how many antigen binding sites?

A

Five - it’s a pentamer; the five Ig units are joined by a J chain

Translates to ten antigen binding sites

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20
Q

IgM is INTRAVASCULAR or EXTRAVASCULAR only?

A

Intravascular - its size precludes it from leaving the bloodstream

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21
Q

Elevated levels of IgM suggest what?

A

Recent infection or exposure

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22
Q

What is the function of IgM?

A

Activates complement system (specifically classical pathway)

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23
Q

Where is IgA produced?

A

Mucosal sites (respiratory and intestinal tracts)

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24
Q

How many Ig chains does IgA have?

A

Two - it’s dimeric with a J chain

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25
Q

Where in the body is IgD found?

A

Blood and lymph fluid

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26
Q

On the surface of what cells is IgD predominantly found?

A

Immature B lymphocytes - functions as an antigen-specific binding site on these cells

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27
Q

IgE is largely bound to surface receptors on what cells?

A

Mast cells and basophils

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28
Q

IgE is found at HIGH/LOW levels in serum

A

Low

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29
Q

What are IgE’s main functions?

A

Allergies
Protection against parasites

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30
Q

Is antigen-antibody binding noncovalent or covalent?

A

Noncovalent. Still a strong bond b/c of hydrophobic bonding, hydrogen bonds, Van Der Waals forces, and ionic interactions

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31
Q

What is the most abundant Ig in the body?

A

IgG - makes of 75% of all antibodies

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32
Q

Which Ig is least abundant in the body?

A

IgD

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33
Q

What is the largest Ig?

A

IgM - pentamer

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34
Q

Which Ig are secretory (found on mucous membranes)?

A

IgA and IgM

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35
Q

Which Ig can cross the placenta?

A

IgG

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36
Q

J chains of Ig are needed for what?

A

Secretion

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37
Q

Which Ig have J chains?

A

IgA and IgM

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38
Q

What Igs are neutralizing Igs?

A

IgG 1-4 and IgA

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39
Q

What are the three mechanisms of antibody action?

A

Neutralization (particularly effective with viruses)
Opsonization
Activation of complement system

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40
Q

The Ab-Ag complex binds to what complement protein to start the complement cascade?

A

C1

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41
Q

The classical complement pathway is triggered by what first step?

A

Antibody binding antigen which then binds C1 protein

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42
Q

Is the alternative complement pathway part of the innate or adaptive immune system?

A

Innate - acts in the absence of Ig

43
Q

What is the common end product of the classical and alternative complement pathways?

A

C3b

44
Q

What does C3b initiate?

A

Terminal pathway

45
Q

What does the terminal pathway result in?

A

Formation of the membrane attack complex

46
Q

C3b can form an immune complex with what CD?

A

CD21

47
Q

T cells express

A

TCR and CD3

48
Q

B cells express

A

Surface membrane Ig and CD79

49
Q

Are NK cells found in the thymus?

A

No

50
Q

NK cells survey for cells with

A

Altered MHC I (aka stressed or damaged cells)

51
Q

Where do NK cells develop?

A

Bone marrow

52
Q

NK cells express what two key cell surface molecules?

A

CD16 and CD56

53
Q

Ab-ag complexes will bind which CD on NK cells to trigger cytotoxicity?

A

CD16

54
Q

NK cells kill via what two pathways?

A

Perforins/granulysin/NK-lysin
CD95L (also known as Fas ligand)

55
Q

Perforins/graulysin/NK-lysin are expressed constitutively in granules of NK cells but are upregulated by which two immunocytokines?

A

IL-2 and IL-12

56
Q

What two cytokines enhance cytotoxicity of NK cells?

A

IL-2 and IL-4

57
Q

What cytokine enhances survival of NK cells?

A

IL-3

58
Q

What cytokine promotes rapid differentiation of pre-NK cells and activates macrophages?

A

INF-gamma

59
Q

What are the primary cytokines of NK cells?

A

INF-gamma (type 2 interferon involved in cell-mediated immunity and Th1 T helper responses)

TNF-alpha

60
Q

What are the three types of antigen presenting cells?

A

Macrophages
Dendritic cells
B lymphocytes

61
Q

The term histiocytes refers to what two types of cells?

A

Dendritic cells and macrophages

62
Q

Macrophages express which MHC class?

A

BOTH - MHC I and II

63
Q

Ingestion of antigens by macrophages causes what effects?

A

Increased lysosomal and bactericidal activity

Upregulates inducible nitric oxide synthase gene which enhances release of NO

64
Q

Macrophages secrete what cytokine to activate naive T-cells (Th1)

A

IL-12

65
Q

What two compounds secreted by macrophages downregulate immune response?

A

IL-10 and TNF-beta

66
Q

From what bone marrow precursor are dendritic cells derived?

A

CD34 BM precursor

67
Q

Where are Langerhans cells located?

A

Epidermis

68
Q

How long do neutrophils circulate before entering tissues, and then how long do they survive?

A

~10 hours
Survive for a few days

69
Q

What are three categories of cell adhesion molecules?

A

Selectins
Integrins
Ig Superfamily Adhesion Molecules

70
Q

What is the function of selectins?

A

Function as lectins which bind CHO moieties expressed by endothelial cells or other WBCs —> helps WBC rolling along vascular endothelium

71
Q

What selectin is found on neutrophils?

A

L-selectin

72
Q

What selectins are found on the endothelium?

A

E-selectin and P-selectin

73
Q

What is the function of integrins?

A

Bind through protein-protein interactions to stop WBC rolling

Mediate aggregation and transendothelial migration

74
Q

What are some examples of integrins?

A

Very Late Antigen (VLA)
Leukocyte function-associated antigen (LFA)
MAC-1

75
Q

What is the function of Ig Superfamily Adhesion Molecules?

A

Stop WBC rolling

Mediate aggregation and transendothelial migration

76
Q

What are some examples of Ig Superfamily Adhesion Molecules?

A

Intercellular Adhesion Molecules (ICAM)
Vascular Cell Adhesion Molecules (VCAMs)
LFA-2
LFA-3

77
Q

What are the stages of WBC emigration during inflammation?

A

Activation
Margination of neutrophils
Rolling/sticking
Stopping/adhesion
Aggregation
Transmigration

78
Q

What molecules are involved in stopping/adhesion during WBC emigration?

A

VLA-4
ICAM
VCAM

79
Q

What molecules are involved in aggregation during WBC emigration?

A

MAC-1
LFA-1
P-selectin

80
Q

What molecules are involved in transmigration during WBC emigration?

A

ICAM
VCAM

81
Q

What happens during the margination step of WBC emigration?

A

Leukocytes move to periphery of vessels due to vasoconstriction and slowing of blood flow

82
Q

What cell adhesion molecules mediate the rolling phase of WBC emigration?

A

Selectins

83
Q

What compounds expressed on neutrophils are involved in firm adhesion/aggregation during WBC emigration?

A

CD11-CD18
VLA-4

84
Q

What happens during the transmigration/diapedesis step of WBC emigration?

A

Neutrophils extend a pseudopod between endothelial cells, digest a small portion of the basement membrane, and emigrate from the vasculature into tissues

85
Q

Neutrophils follow what to the site of infection? What factors are involved?

A

Chemotactic gradient

Chemotactic factors: C5a, C3b, fibrin, kinin

86
Q

What part of the endothelium helps initiate the migration of leukocytes into tissues?

A

P and E selectin

87
Q

What are two Opsonization that bind the Fc receptor?

A

IgG and C3b

88
Q

Via what two processes do neutrophils destroy ingested bacteria?

A

Respiratory burst
Release of lyric enzymes and anti microbial peptides

89
Q

Respiratory burst is O2 ____ and release of lyric enzymes/anti microbial peptides is ____.

A

Respiratory burst = oxygen dependent

Release of lyric enzymes/antimicrobial peptides = oxygen independent

90
Q

How does respiratory burst work?

A

NADPH oxidase enzyme complex results in formation of potent bactericidal oxidants (H2O2, hypochloride ions)

91
Q

What are differences between perforins and defensins?

A

Perforins:
-Released by granules of cytotoxic T cells and NK cells
-Form a hole in the target cell membrane that allows granzyme to enter and degrade the cell’s DNA, which results in apoptosis

Defensins:
-Act as direct chemoattractants for immature dendritic cells
-Some are opsonic
-They target any organism with a cholesterol-free negatively charged membrane (bacteria, fungi, many viruses)
-Can compromise 50% of protein in azurophil (primary) phagocytic granules
-Found within neutrophil granules and epithelial cells to assist in killing phagocytized bacteria

92
Q

Where are defensins found?

A

Primary granules of neutrophils and epithelial cells

93
Q

What are characteristics of defensins?

A

-Highly cytotoxic
-Arginine-rich cationic proteins
-Form voltage-gated ion channels in bacterial cell membranes resulting in increased permeability

94
Q

What are two examples of defensins?

A

Defensin-alpha (DEFA)
Defensin-beta (DEFB)

95
Q

Pathogen associated molecular patterns and damage associated molecular patterns are recognized by what receptors?

A

Pattern recognition receptors

96
Q

What portion of the cell wall is recognized by PRRS in Gram-positive bacteria?

A

Peptidoglycans

97
Q

What portion of the cell wall is recognized by PRRs in Gram-negative bacteria?

A

Lipopolysaccharide (LPS)

98
Q

What portion of the cell wall is recognized by PRRs in acid fast bacteria?

A

Glycolipids

99
Q

What portion of the cell wall is recognized by PRRs in yeast?

A

Mannan- or B-glucan rich cell wall

100
Q

What portion of the cell wall is recognized by PRRs in viruses?

A

Nucleic acids

101
Q

What is the most significant family of pattern recognition receptors?

A

Toll like receptors (TLRs)

102
Q

On what cells are TLRs found?

A

Sentinel cells of the innate immune system:
Macrophages
Neutrophils
Mast cells
Dendritic cells

T and B cells of the adaptive immune system

Non-immune cells (epithelial cells that line respiratory and GIT)

103
Q

What happens when toll like receptors are activated?

A

Turn on genes for production of pro inflammatory factors = INFLAMMATION