Immunology Flashcards
1
Q
innate immune system
A
protection that exists before the infection occurs
non-specific and rapid; no memory component (except for Natural Killer cells, who have been shown to have some memory aspects
2
Q
adaptive immune system
A
protection stimulated by exposure to an infectious agent
specific and provides immunity or resistance against a particular pathogen
slower to respond to antigens but has a memory component
3
Q
branch of immune system for neutrophils
A
innate
4
Q
branch of immune system for macrophages
A
innate
5
Q
branch of immune system for eosinophil
A
innate
6
Q
branch of immune system for basophils
A
innate
7
Q
branch of immune system for dendritic cells
A
innate
8
Q
five antibody isotypes
A
IgM IgE IgG IgA IgD
determined by the type of constant regions on the heavy chain (Fc region)
[immunoglobulins prevent MEGA Death]
9
Q
branch of immune system for immunoglobulins
A
adaptive
10
Q
IgM main function
A
antigen receptor on B-Cell surface
fixes complement
11
Q
IgA main functions
A
prevents attachment of pathogen to mucous membranes
high concentration in breast milk in order to transfer immunity to newborn infants
12
Q
IgD main function
A
not yet determined
present on surface of B-Cells, where it functions as a receptor for antigens
13
Q
IgE main functions
A
main host defense against helminth infections and allergy
causes release of histamine from mast cells and basophils upon exposure to allergens
causes release of enzymes from eosinophils in defense against worm infections
14
Q
lymphocytes
A
cells that mediate immune responses and that are found in blood, lymphoid tissues and virtually all organs
T, B, and NK (Natural Killer) cells
15
Q
phagocytes
A
eat and kill microbes: neutrophils (also called polymorphonuclear cells or PMNs), macrophages and dendritic cells
16
Q
cellular immunity
A
refers to the functions that immune cells perform
17
Q
humoral immunity
A
refers to the functions performed by proteins found in bodily fluids
18
Q
complement system
A
a system of proteins that functions to attract immune cells to sites of infection (inflammation) and also binds to microbes marking them for phagocytosis (opsonization)
19
Q
microbial lysis
A
killing microbes by punching holes in their membranes
20
Q
antibody
A
a glycoprotein produced by a type of lymphocyte called a B lymphocyte (B cell for short) which specifically binds and is generated against its antigen
also called immunoglobulin or Ig for short
21
Q
antigen
A
what binds to an antibody
usually a microbe or a microbial product
22
Q
antibody purpose
A
attach to its antigen in order to:
take away their ability to invade or damage body tissues (neutralization)
mark microbes for phagocytosis (opsonization)
attract complement proteins and let complement do its jobs
23
Q
opsonization
A
when antibodies bind to antigens to mark them for phagocytosis
24
Q
neutralization
A
when antibodies bind to antigens take away their ability to invade or damage body tissues
25
neutrophils main function
granulocyte, 1st cell to migrate to infection site. predominant cell in pus
26
neutrophils mechanism
upon infection, releases granules, phagocytosis, and Neutrophil Extracellular Traps (NET)
27
neutrophils overview
these granulocytes (d/t having granules) have a nucleus that has multiple lobes that can take on many shapes (sometimes they are called polymorphonuclear cells or PMNs)
their granules aren’t exclusively one type or the other (basic or acidic) when stained
most abundant circulating white blood cell
28
two types of neutrophil granules
granules that stain pink (because they take up an acidic dye in a routine blood stain)
granules that stain blue (because they take up a basic dye in a routine blood stain)
29
basophils structure
granulocytes with granules that are exclusively the type that attracts the basic (blue) dye
secrete these granules, which contain histamine and heparin
30
eosinophils structure
granulocytes with a cytoplasm that is filled with large granules that exclusively attract the acidic (pink) dye (because the acidic dye is eosin)
the granules contain enzymes and proteins with various (known and unknown) functions
31
the primary composition of pus
neutrophils
32
eosinophils main function
granulocytes that respond to anti-parasitic and bactericidal activity
also respond to allergic rxns and modulate the inflammatory response
33
basophils main function
granulocyte that plays a role in inflammation, and immune response when fighting infection caused by parasites
also plays a role in preventing blood clots via heparin
34
macrophages main functions
identifying, destroying, and removing foreign substances from the body
engage in antigen presentation and cytokine production (TNF-alpha and IL-1)
recognize viral components via macrophage Pattern Recognition Receptors (PRR)
35
macrophages overview
phagocyte found mainly in tissues with many other roles in communication and coordination
```
they:
kill (phagocytose microbes)
talk (secrete and respond to cytokines)
clean (clear dead cells)
heal (begin process of tissue repair)
```
36
dendritic cells' main functions
engage in phagocytosis before traveling to lymph nodes to present microbial antigens to T-cells
professional antigen-presenting cell (APC)
express costimulatory molecules and MHC II protein
secrete cytokines
37
dendritic cells overview
phagocyte and APC found in tissues
key players in bridging innate and adaptive immune responses.
38
phagocytosis
the process by which certain cells of the innate immune system (phagocytes) engulf large particles such as intact microbes leading to the formation of an intracellular vesicle called a phagosome that contains the ingested particle
fusion of phagosomes with lysosomes results in enzymatic digestion of the ingested material.
39
PMNs
polymorphonuclear leukocyte; another name for neutrophils
40
antibody structure
each antibody molecule is composed of 2 identical heavy chains and 2 identical light chains (either k or l) and has an antigen-binding site that is identical (each site binds the same antigen)
41
antigen-binding site structure
each antigen-binding site on an antibody molecule is identical (each site binds the same antigen)
42
Fab fragment definition and structure
fragment antigen binding
each antibody monomer contains two Fab fragments and each Fab fragment has one antigen-binding site composed of a variable region of one heavy and one light chain
43
Fc fragment definition and structure
fragment crystalline or constant
each antibody monomer contains one Fc fragment composed of heavy chain constant regions
44
IgG main functions
opsonization
neutralization
fixes complement
45
IgG overview
most abundant antibody in the blood
main antibody in secondary response
able to cross the placenta
46
IgM overview
produced as a pentamer during primary response to antigen
has higher avidity for viral antigen than IgG
cannot cross the placenta due to size
47
affinity (antibody)
strength of interaction between an antigen-binding site and an antigen
48
avidity
cumulative strength of all the antigen-binding sites on an antibody molecule
49
epitope
exact part of the antigen that binds to the antibody (one antigen can have several epitopes)
50
immunogen
antigen that is capable of producing an immune response
| not every antigen is an immunogen, e.g. self-antigens are not immunogenic
51
IgA major feature
usually dimeric
52
which isotypes activate classical complement pathway
IgG (IgG1, IgG3) & IgM
53
the most abundant immunoglobulin in serum
IgG
54
IgD expression
only expressed in combination with IgM on the surface of naïve mature B cells
55
immunoglobulin that has the longest half life
IgG (almost a month)
IgA, then IgM rank next in abundance and in half-life
56
IgA serum concentration (mg/mL) and serum half-life (days)
3.5 mg/mL
6 days
57
IgM serum concentration (mg/mL) and serum half-life (days)
1.5 mg/mL
5 days
58
IgG serum concentration (mg/mL) and serum half-life (days)
13.5 mg/mL
23 days
59
IgD serum concentration (mg/mL) and serum half-life (days)
trace
3
60
IgE serum concentration (mg/mL) and serum half-life (days)
0.05 mg/mL
2 days
61
chemokines
a large family of molecules that stimulate and regulate leukocyte migration
(they tell the cells of the immune system where to go)
62
Fc region function overview
determines an antibody’s effector function
63
how do Fc receptors effect opsonization
Fc receptors (FcγRI) on phagocytes bind IgG1 or IgG3 on microbe, assists phagocytosis
64
what causes mast cells, basophils, and eosinophils to degranulate
when an IgE molecule that is bound to their Fc receptors (FcεR1) is cross-linked by an antigen (helminth or allergen)
65
branch of immune system for mast cells
innate
66
degranulation
the process by which mast cells or neutrophils release the contents of their granules into the surrounding tissues
67
branch of immune system for monocytes
innate
68
branch of immune system for Natural Killer cells
innate
69
branch of immune system for granulocytes
innate
| granulocytes = neutrophils, eosinophils, basophils
70
branch of immune system for compliment proteins
innate
71
complement system
a collection of circulating and membrane-associated proteins that are important in the defense against microbes
many complement proteins are proteolytic enzymes that require sequential activation
72
complement system steps
1: Binding of complement proteins to microbial cell surface or antibody
2: Formation of C3 convertase
3: Cleavage of C3
4: Binding of C3b and formation of C5 convertase
5: Formation of Membrane Attack Complex (MAC)
73
C3 convertase function
catalyzes cleavage of C3 into C3a and C3b
74
C3a functions
stimulates inflammation
chemotaxis
vasodilation
phagocyte activation
[same as C5a functions]
75
other names for C3 convertase
4bC2b (formerly C4bC2a) (classical and lectin pathway)
C3bBb (alternative pathway)
76
C3b functions
opsonizes microbes
binds to CR1 on phagocytes
77
C5 convertase function
catalyzes cleavage of C5 and to C5a and C5b
78
other names for C5 convertase
C4bC2bC3b (classical and lectin pathway)
C3bBbC3b (alternative pathway)
79
C5a functions
stimulates inflammation
chemotaxis
vasodilation
phagocytic activation
[same as C3a functions]
80
C5b function
initiates assembly of the membrane attack complex (MAC)
81
CR1 function
complement receptor which binds C3b and is expressed on phagocytes
82
branch of immune system for T-Cells
adaptive
83
branch of immune system for B-Cells
adaptive
84
branch of immune system for CD4 T Helper Cells
adaptive
85
branch of immune system for CD8 T-Cells
adaptive
86
mast cells overview
granulocytes with a role in allergy and anaphylaxis
upon stimulation by an allergen, mast cells release the contents of their granules into surrounding tissues
87
monocytes overview
facilitate healing a repair, and can differentiate into macrophages or dendritic cells
produce cytokines (mainly TNF, IL-1, and IL-12)
88
Natural Killer cells overview
lymphocytes of innate immunity found in the blood and throughout the body, which directly kill microbe-infected cells by secreting cytokines that activate phagocytes or cause apoptosis
they act when they detect “changed” or “stressed” cells (i.e. virally infected cells)
89
granulocytes overview
neutrophils, basophils, eosinophils
contain large, cytoplasmic granules which are used to secrete important substances, such as enzymes and chemicals
granules help fight off infection and have a distinguishable morphology that can be stained by basic dyes (blue = basic, pink = acidic)
90
compliment proteins overview
a system comprised of various plasma proteins that react with one another to opsonize pathogens and induce a series of inflammatory responses that help to fight infection
activated through an enzyme-triggered cascade
91
CD8+ cytotoxic T-Cell (CTL) overview
an effector T-cell which is specific for MHC I protein
involved in the lysis of infected or cancerous cells, by poking a hole into cells and injecting molecules that cause the cells to commit suicide (similar to NK cells but more selective, look for MHC I protein)
releases perforin and granzymes to elicit cytotoxicity function
92
T-Cells overview
the most numerous type of lymphocyte found in the blood, and also found in lymph nodes and tissues
produced by bone marrow as immature T-cells, which then travel to the thymus [hence the T] and mature into unique, naïve T cells
naïve T cells leave the thymus and migrate between lymph nodes looking for an antigen to which they can bind, and once bound, it becomes activated, proliferates and its progeny mature into effector and memory T cells
93
B-Cells overview
lymphocyte found in the blood and lymph nodes (mostly in the lymph nodes)
produced by Bone marrow [hence the B] as unique, naïve B cells which then wander from lymph node to lymph node looking for an antigen to which they can bind.
when it finds an antigen to which it can bind, it becomes activated, proliferates and its progeny mature into both effector cells and memory cells
94
CD4+ Helper T-Cells (TH) overview
effector T-Cell which is specific for MHC II protein; communicate with macrophages and secrete cytokine to activate other cells
help B cells to mature into antibody-secreting plasma cells
assist in the activation of CD8+ cytotoxic T cell (CTL)
95
compliment protein system three distinct pathways
classical
alternative
manose-binding-lectin
96
two branches of the innate immune system
cellular & humoral
97
what makes B-cells "naïve" and "unique"
they are naïve because these B cells have not yet encountered an antigen capable of binding to this unique molecule
they are unique because each has a unique molecule on their cell surface called the B cell antigen receptor (BCR)
98
effector cells
antibody-secreting plasma cells created from B-cells
E.g. CD4+ Helper T, CD8+ cytotoxic T-cell
99
what makes T-cells "naïve" and "unique"
they are naïve because these T cells have not yet encountered an antigen capable of binding to this unique molecule
they are unique because each has a unique molecule on their cell surface called the T cell antigen receptor (TCR)
100
effector T cells main function
control immune responses [the “kings” of cell-mediated immunity]
101
AIDS patients are deficient in what immune cell
CD4+ TH cells
102
generative lymphoid organs
thymus & bone marrow [b/c they generate T and B-cells, respectively]
also called the central lymphoid organs or primary lymphoid organs
103
secondary lymphoid organs
lymph nodes, spleen, and mucosal and cutaneous lymphoid tissue [since naïve B and T-cells meet here for antigens second]
also called peripheral lymphoid organs
104
active immune response
when the body encounters an antigen causing naïve B and T cells to proliferate and mature into effector and memory cells, and thus the effector B cells make an antibody
lasts longer than the passive immune response
105
passive immune response
when a premade antibody is administered to an individual and their immune system does not have to effector B-cells make antibodies
does not last as long as active immune response
106
secondary response
the second time we are exposed to an antigen
faster, greater magnitude, and has a different antibody-type with a higher affinity than the primary response
107
primary response
the first time we are exposed to an antigen
slower, lesser magnitude, and has different antibody-types with a decreased affinity than the secondary response
108
cytokines
the molecules by which cells of the immune system communicate with other cells
[Cyto = cell, kine = do something]
109
chemokines
cytokines with the primary function of enacting movement
[Chemo = a small molecule, almost chemical-like; kine = do something, which in this case is move!]
110
naïve lymphocytes
T or B lymphocytes (not NK cells because they do not bind antigen) that have never encountered an antigen to which they can bind
(these cells only live for a few weeks/months)
111
effector lymphocytes
T or B lymphocytes that have encountered an antigen to which they can bind and are programmed to perform their function immediately
these cells only live for a few days
112
memory lymphocytes
T or B lymphocytes that have encountered an antigen to which they can bind and are programmed to be memory cells
these cells live quiescently for years and reactivate quickly when they encounter their antigen
113
where are B-cells found in lymph nodes
the follicles
114
where are T-cells found in lymph nodes
in the paracortex
115
where are dendritic cells found in lymph nodes
in the paracortex
116
high endothelial venules (HEVs)
specialized venules in lymph nodes through which naive T-cells enter
117
where is the highest probability for a naïve T cell to see its antigen
in lymph nodes where it is concentrated
