Immunology Flashcards
1
Q
What is the definition of a true autoimmune disease?
A
Loss of immune tolerance to your own tissues
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
3
Q
What are the inflammatory mediators of the innate immune system?
A
Chemokines and cytokines
4
Q
Which pathway of the complement system involves the innate immune system?
A
Alternate pathway
5
Q
Fever is mediated by what pyrogenic cytokines?
A
IL-1
IL-6
TNF-alpha
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
7
Q
What is peripheral tolerance?
A
Inability of mature T and B cells to pathologically respond to self
8
Q
What is an alloantigen?
A
Tissue from genetically dissimilar individuals of the SAME species
9
Q
What is a xenoantigen?
A
Tissue from genetically dissimilar individuals of a DIFFERENT species
10
Q
What is an autoantigen?
A
A component of the host’s body that becomes antigenic
11
Q
What is a superantigen?
A
Bacterial or retrovial products that bind directly to MHC II outside the antigen binding groove
12
Q
Superantigens bind the T cell receptor outside the conventional binding site with specificity for what chain?
A
Beta chain
13
Q
What is an epitope?
A
The part of an antigen that is capable of inducing an immune response
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)
15
Q
What immunoglobulin is the major serum immunoglobulin?
A
IgG
16
Q
Where is IgG found?
A
Blood and ECF
17
Q
What are IgG’s two main functions?
A
Opsonization
Virus neutralization
18
Q
What is the first immunoglobulin produced during humoral responses?
A
IgM
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
20
Q
IgM is INTRAVASCULAR or EXTRAVASCULAR only?
A
Intravascular - its size precludes it from leaving the bloodstream
21
Q
Elevated levels of IgM suggest what?
A
Recent infection or exposure
22
Q
What is the function of IgM?
A
Activates complement system (specifically classical pathway)
23
Q
Where is IgA produced?
A
Mucosal sites (respiratory and intestinal tracts)
24
Q
How many Ig chains does IgA have?
A
Two - it’s dimeric with a J chain
25
Where in the body is IgD found?
Blood and lymph fluid
26
On the surface of what cells is IgD predominantly found?
Immature B lymphocytes - functions as an antigen-specific binding site on these cells
27
IgE is largely bound to surface receptors on what cells?
Mast cells and basophils
28
IgE is found at HIGH/LOW levels in serum
Low
29
What are IgE’s main functions?
Allergies
Protection against parasites
30
Is antigen-antibody binding noncovalent or covalent?
Noncovalent. Still a strong bond b/c of hydrophobic bonding, hydrogen bonds, Van Der Waals forces, and ionic interactions
31
What is the most abundant Ig in the body?
IgG - makes of 75% of all antibodies
32
Which Ig is least abundant in the body?
IgD
33
What is the largest Ig?
IgM - pentamer
34
Which Ig are secretory (found on mucous membranes)?
IgA and IgM
35
Which Ig can cross the placenta?
IgG
36
J chains of Ig are needed for what?
Secretion
37
Which Ig have J chains?
IgA and IgM
38
What Igs are neutralizing Igs?
IgG 1-4 and IgA
39
What are the three mechanisms of antibody action?
Neutralization (particularly effective with viruses)
Opsonization
Activation of complement system
40
The Ab-Ag complex binds to what complement protein to start the complement cascade?
C1
41
The classical complement pathway is triggered by what first step?
Antibody binding antigen which then binds C1 protein
42
Is the alternative complement pathway part of the innate or adaptive immune system?
Innate - acts in the absence of Ig
43
What is the common end product of the classical and alternative complement pathways?
C3b
44
What does C3b initiate?
Terminal pathway
45
What does the terminal pathway result in?
Formation of the membrane attack complex
46
C3b can form an immune complex with what CD?
CD21
47
T cells express
TCR and CD3
48
B cells express
Surface membrane Ig and CD79
49
Are NK cells found in the thymus?
No
50
NK cells survey for cells with
Altered MHC I (aka stressed or damaged cells)
51
Where do NK cells develop?
Bone marrow
52
NK cells express what two key cell surface molecules?
CD16 and CD56
53
Ab-ag complexes will bind which CD on NK cells to trigger cytotoxicity?
CD16
54
NK cells kill via what two pathways?
Perforins/granulysin/NK-lysin
CD95L (also known as Fas ligand)
55
Perforins/graulysin/NK-lysin are expressed constitutively in granules of NK cells but are upregulated by which two immunocytokines?
IL-2 and IL-12
56
What two cytokines enhance cytotoxicity of NK cells?
IL-2 and IL-4
57
What cytokine enhances survival of NK cells?
IL-3
58
What cytokine promotes rapid differentiation of pre-NK cells and activates macrophages?
INF-gamma
59
What are the primary cytokines of NK cells?
INF-gamma (type 2 interferon involved in cell-mediated immunity and Th1 T helper responses)
TNF-alpha
60
What are the three types of antigen presenting cells?
Macrophages
Dendritic cells
B lymphocytes
61
The term histiocytes refers to what two types of cells?
Dendritic cells and macrophages
62
Macrophages express which MHC class?
BOTH - MHC I and II
63
Ingestion of antigens by macrophages causes what effects?
Increased lysosomal and bactericidal activity
Upregulates inducible nitric oxide synthase gene which enhances release of NO
64
Macrophages secrete what cytokine to activate naive T-cells (Th1)
IL-12
65
What two compounds secreted by macrophages downregulate immune response?
IL-10 and TNF-beta
66
From what bone marrow precursor are dendritic cells derived?
CD34 BM precursor
67
Where are Langerhans cells located?
Epidermis
68
How long do neutrophils circulate before entering tissues, and then how long do they survive?
~10 hours
Survive for a few days
69
What are three categories of cell adhesion molecules?
Selectins
Integrins
Ig Superfamily Adhesion Molecules
70
What is the function of selectins?
Function as lectins which bind CHO moieties expressed by endothelial cells or other WBCs —> helps WBC rolling along vascular endothelium
71
What selectin is found on neutrophils?
L-selectin
72
What selectins are found on the endothelium?
E-selectin and P-selectin
73
What is the function of integrins?
Bind through protein-protein interactions to stop WBC rolling
Mediate aggregation and transendothelial migration
74
What are some examples of integrins?
Very Late Antigen (VLA)
Leukocyte function-associated antigen (LFA)
MAC-1
75
What is the function of Ig Superfamily Adhesion Molecules?
Stop WBC rolling
Mediate aggregation and transendothelial migration
76
What are some examples of Ig Superfamily Adhesion Molecules?
Intercellular Adhesion Molecules (ICAM)
Vascular Cell Adhesion Molecules (VCAMs)
LFA-2
LFA-3
77
What are the stages of WBC emigration during inflammation?
Activation
Margination of neutrophils
Rolling/sticking
Stopping/adhesion
Aggregation
Transmigration
78
What molecules are involved in stopping/adhesion during WBC emigration?
VLA-4
ICAM
VCAM
79
What molecules are involved in aggregation during WBC emigration?
MAC-1
LFA-1
P-selectin
80
What molecules are involved in transmigration during WBC emigration?
ICAM
VCAM
81
What happens during the margination step of WBC emigration?
Leukocytes move to periphery of vessels due to vasoconstriction and slowing of blood flow
82
What cell adhesion molecules mediate the rolling phase of WBC emigration?
Selectins
83
What compounds expressed on neutrophils are involved in firm adhesion/aggregation during WBC emigration?
CD11-CD18
VLA-4
84
What happens during the transmigration/diapedesis step of WBC emigration?
Neutrophils extend a pseudopod between endothelial cells, digest a small portion of the basement membrane, and emigrate from the vasculature into tissues
85
Neutrophils follow what to the site of infection? What factors are involved?
Chemotactic gradient
Chemotactic factors: C5a, C3b, fibrin, kinin
86
What part of the endothelium helps initiate the migration of leukocytes into tissues?
P and E selectin
87
What are two Opsonization that bind the Fc receptor?
IgG and C3b
88
Via what two processes do neutrophils destroy ingested bacteria?
Respiratory burst
Release of lyric enzymes and anti microbial peptides
89
Respiratory burst is O2 ____ and release of lyric enzymes/anti microbial peptides is ____.
Respiratory burst = oxygen dependent
Release of lyric enzymes/antimicrobial peptides = oxygen independent
90
How does respiratory burst work?
NADPH oxidase enzyme complex results in formation of potent bactericidal oxidants (H2O2, hypochloride ions)
91
What are differences between perforins and defensins?
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
Where are defensins found?
Primary granules of neutrophils and epithelial cells
93
What are characteristics of defensins?
-Highly cytotoxic
-Arginine-rich cationic proteins
-Form voltage-gated ion channels in bacterial cell membranes resulting in increased permeability
94
What are two examples of defensins?
Defensin-alpha (DEFA)
Defensin-beta (DEFB)
95
Pathogen associated molecular patterns and damage associated molecular patterns are recognized by what receptors?
Pattern recognition receptors
96
What portion of the cell wall is recognized by PRRS in Gram-positive bacteria?
Peptidoglycans
97
What portion of the cell wall is recognized by PRRs in Gram-negative bacteria?
Lipopolysaccharide (LPS)
98
What portion of the cell wall is recognized by PRRs in acid fast bacteria?
Glycolipids
99
What portion of the cell wall is recognized by PRRs in yeast?
Mannan- or B-glucan rich cell wall
100
What portion of the cell wall is recognized by PRRs in viruses?
Nucleic acids
101
What is the most significant family of pattern recognition receptors?
Toll like receptors (TLRs)
102
On what cells are TLRs found?
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
What happens when toll like receptors are activated?
Turn on genes for production of pro inflammatory factors = INFLAMMATION
