Immune Function Flashcards
1
Q
what is immunity?
A
collective set of defenses against a wide variety of potential threats
2
Q
what does immunity consist of?
A
pathogens
toxins
abnormal cells (cancer)
foreign cells (transplants)
3
Q
innate immunity
A
present at birth
nonspecific-behaves same way regardless of threat
4
Q
adaptive immunity
A
develops after exposure to threat
specifically identifies threat and maintains memory
5
Q
where do most adaptive immune responses occur?
A
within lymphatic system
6
Q
what percent of circulating WBCs are lymphocytes?
A
20-30%
7
Q
lymphocytes
A
not phagocytic
most reside in lymphatic system
key players in adaptive immunity
8
Q
lymphatic system components
A
lymph
lymphatic vessels
lymphatic tissues & organs
lymphatic cells-lymphocytes & others
9
Q
lymphatic system functions
A
produces & “activates” lymphocytes
returns excess interstitial fluid to bloodstream
transports lipids from digestive tract
10
Q
lymphatic system-produces & “activates” lymphocytes
A
red bond marrow & thymus
tonsils, MALT, lymph nodes & spleen
11
Q
lymphatic system-returns excess interstitial fluid to bloodstream
A
maintain normal blood volume
12
Q
lymphatics
A
carry interstitial fluid that has “leaked” from capillaries to venous system
converge & empty into two major collecting vessels
13
Q
two main collecting vessels of lymphatic system
A
thoracic duct
right lymphatic duct
14
Q
thoracic duct
A
receives 85% of body lymph
empties into left subclavian vein
15
Q
right lymphatic duct
A
receives 15% of body lymph
empties into right subclavian vein
16
Q
lymphoid tissues
A
lack connective tissue capsule
associated with systems possessing external opening(s)
17
Q
respiratory lymphoid tissues
A
tonsils
18
Q
digestive lymphoid tissues
A
MALT (mucosa-associated lymphoid tissue)
19
Q
other lymphoid tissues
A
urinary and reproductive
20
Q
lymphoid tissues contain
A
high concentration of lymphocytes
21
Q
lymphoid tissues function
A
defend portals of entry for pathogens
22
Q
lymphoid organs
A
possess a connective tissue capsule
thymus, lymph nodes and spleen
23
Q
thymus location
A
superior mediastinum
24
Q
thymus site of
A
site of T-cell programming and maturation
25
how long is thymus functional?
becomes nonfunctional after puberty
| undergoes atrophy and replaced by fat
26
lymph nodes location
lie along courses of lymphatics
neck, axilla, groin
afferent/efferent lymphatics
27
cortex of lymph nodes
B lymphocytes
28
paracortex of lymph nodes
T lymphocytes
29
medulla of lymph nodes
efferent lymphatic and vasculature
30
what are lymph nodes the sites of?
antigen recognition by B and T lymphocytes
31
what do lymph nodes do in response to infection?
enlarge
32
what happens to lymph?
it is purified in lymph nodes before returned to blood
33
spleen function, location
multifunctional, nonessential
| LUQ of abdomen
34
spleen-red pulp
removes, recycles old RBC
stores iron
stores platelets
35
spleen-white pulp
stores B and T lymphocytes
same arrangement as nodes
monitor circulating blood for antigen recognition
36
lymphoid cells-lymphocytes
all derived from red bone marrow
37
types of lymphocytes
T cells
B cells
NK cells
Macrophages and dendritic cells
38
T cells
80% of circulating lymphocytes
| responsible for "cell-mediated" immunity
39
B cells
15% of circulating lymphocytes
| responsible for "antibody-mediated" (humoral) immunity
40
NK cells
5% of circulating lymphocytes
| role in innate immunity
41
macrophages and dendritic cells
important in "antigen presentation"
42
innate immunity characteristics
same response against any type of threat
no memory
mainly important in defense against pathogens
43
innate immunity levels
```
physical/chemical barriers
phagocytosis
immune surveillance
complement
inflammation
fever
```
44
innate immunity-physical barriers
skin
| epithelium of internal cavities and pathways
45
innate immunity-chemical barriers
some epithelium produce flushing secretions
-sweat, sebum, mucus
some produce secretions that kill/inhibit pathogens
-stomach acid, lysozyme in tears, antibodies in breast milk
46
phagocytic cells
neutrophils and eosinophils
monocytes/macrophages
-migrate towards chemotaxins
-phagocytosis enhanced by opsonins
47
monocytes/macrophages types and locations
free-circulate in blood/lymph
fixed-reside in tissues
-liver-kupffer cells
-CNS-microglia
48
what is the function of NK lymphocytes?
immune survelliance
49
what do NK cells do?
recognize and adhere to abnormal cell surface proteins
expressed by virally-infected cell or some tumor cells
"self" surface proteins prevent NK cell killing
50
what do NK cells secrete?
"perforins"
51
what do perforins do?
result in rupture of abnormal or infected cells
52
complement system components
over 30 plasma proteins
53
how does the complement system work?
plasma proteins react together in chain reactions or "pathways"
- similar to coagulation pathways
- some protein fragments have biological activity
54
classical pathway
activated by Ag-Ab complexes (adaptive immunity)
55
alternate pathway
activated by pathogen cell surface proteins (innate immunity)
56
lectin pathway
starts classical pathway in absence of Ag-Ab complexes
57
what is the endpoint of all complement pathways?
cleavage of C3 to C3a and C3b
58
C3b
powerful opsonin-enhances phagocytosis
| cleaves C5 to C5a and C5b
59
C5a
chemotaxis-attracts neutrophils
60
C3a and C5a
anaphylatoxins-stimulate histamine release from mast cells and basophils
vasodilation, increased capillary permeability
61
C5b
joins C6-C9 to form membrane attack complex (MAC)
| punches holes in pathogen membranes
62
inflammation
localized tissue response to injury or infection
63
inflammation characteristics
red, hot, swollen, painful, plus or minus loss of function
64
what happens in inflammation?
walls off area of injury/infection
removes offending agent and/or devitalized tissue
sets stage for permanent repair (regeneration)
65
fever
body temperature >37.2 C
66
what happens during fever?
accelerates WBC activity
| inhibits some viruses and bacteria
67
fever-inducing agents
produced by some pathogens
endogenous pyrogens
interleukin-1 and tumor necrosis factor
68
treating fever
do not treat just to treat, ask why
69
adaptive immunity
AKA "immune response"
| results from the coordinated activities of B & T lymphocytes
70
adaptive immunity-2 lines of defense
cell-mediated immunity
| antibody-mediated (humoral) immunity
71
what is involved in cell-mediated immunity?
T cells
| most important for intracellular pathogens & abnormal/foreign cells
72
what is involved in antibody-mediated (humoral) immunity?
B cells
| most important for extracellular pathogens
73
what do both lines of defense (cell mediated and antibody mediated) in adaptive immunity do?
both recognize, respond to and remember threats based on specific antigens
74
T cells
80% of circulating lymphocytes
75
where do T cells mature
mature and acquire specificity for antigen in thymus
76
what dictates T cell specificity?
T cell receptor gene rearrangements before birth
77
what distinguishes T cell types?
cluster of differentiation (CD) markers on cell surface
78
general T cell markers
CD3, CD28
79
what marker denotes cytotoxic T cells or NK cells?
CD8 or T8
80
what do T8 cells do?
effector cells that directly attack foreign antigens
81
what marker denotes helper T cells?
CD4 or T4
82
what do helper T4 cells do?
helper T cells are the master regulatory cells of immune response
83
what marker denotes regulatory T cells?
CD4, CD25
84
what do regulatory T cells do?
suppress immune response
85
B cells
15% of circulating lymphocytes
86
where do B cells mature?
B cells mature and acquire specificity for antigen in bone marrow
87
what dictates B cell specificity?
specificity for antigen dictated by immunoglobulin gene rearrangements before birth
88
what do mature B cells express?
mature B cells express immunoglobulin on surface (B cell receptor)
89
what do B cells differentiate into?
B cells differentiate into plasma cells upon activation
90
what do plasma cells do?
produce immunoglobulins (antibodies)
91
antigens (foreign)
molecules that elicit an immune response
92
types of antigens
pathogen cell surface proteins
toxins
abnormal/foreign cell surface proteins
etc
93
where do T and B cells bind
a specific portion of an antigen known as epitope
94
specificity of T and B cells
each T or B cell is specific to one antigen only
95
haptens
atoms or small molecules that act as antigens only when bound to larger protein
96
examples of haptens
nickel atoms binding to skin keratin
poison ivy wax binding to skin keratin
most idiosyncratic drug reactions
97
what activates the cell?
antigen/hapten binding to T or B cell receptor
98
what do activated lymphocytes do?
multiply to form clones
99
four properties of adaptive immunity
specificity
versatility
memory
tolerance
100
specificity
each T or B cell responds to only one specific antigen
101
versatility
many different lymphocytes with limitless receptor specificities are produced
if activated will clone to combat a specific antigen
102
memory
some activated lymphocytes (memory cells) remain in circulation
provide more rapid defense against subsequent exposure
103
tolerance
immune system ignores "normal" antigens (self-antigens)
104
what are major histocompatibility complex (MHC) molecules?
"self" antigens encoded by MHC genes on chromosome 6
| 128 genes divided into 3 classes
105
class I and II MHCs
code for human leukocyte antigens (HLA)
106
class I MHCs code for _____
HLA-A, HLA-B, and HLA-C antigens
107
class II MHCs code for _____
HLA-DQ, HLA-DP, HLA-DR antigens
108
what determines tissue "type" used in transplantation matching?
6 antigens: HLA A, B, C, DQ, DP, DR
109
what can different HLA antigens also indicate?
predisposal to various diseases
110
what antigen is related to ankylosing spondylitis?
HLA-B27
111
what antigen is related to Graves' disease?
HLA-DR3
112
what do MHC I and II proteins allow?
lymphocytes to distinguish between foreign and "self" antigens
113
MHC I proteins
```
MHC I proteins present on ALL nucleated cells
function to transport foreign molecules (antigens) to cell surface
```
114
how do CD8 cytotoxic T cells see antigen?
only when complexed with MHC I
115
what happens after CD8 cytotoxic T cell sees antigen?
kills cell bearing foreign antigen
116
what kind of cells do cytotoxic T cells kill?
virally-infected cells
| some cancer cells have MHC I that T cells "see" as foreign
117
MHC II proteins present on
only macrophages and B cells
118
function of MHC II proteins
transport fragments of engulfed molecules (antigens) to cell surface
119
function of MHC I proteins
transport foreign molecules (antigens) to cell surface
120
how do CD4 helper T cells see antigen?
only when complexed with MHC II
121
what does helper T cell do after it sees antigen?
secretes cytokines to activate immune response
122
cell mediated immunity cytotoxic T cells activated
inactive Tc cells activated by binding of TCR to MHC-I antigen complex
123
what happens after Tc cell activated?
Tc cell divides
124
what do Tc cells divide into?
Tc cells specific to same antigen
memory Tc cells
regulatory T cells (later)
125
how to Tc cells kill infected/cancerous cell?
secretion of toxins
126
what toxins do T3 cells secrete?
perforin
lymphotoxin
cytokines that trigger apoptosis
127
memory Tc cells
produced with cytotoxic T cells
stay in circulation
immediately form cytotoxic T cells if same antigen reencountered
128
regulatory T cells
produced late
secrete suppression factors
inhibit responses of T and B cells
limit immune response to single stimulus
129
T helper cell activation
Inactive Th cells activated by binding of TCR to MHC II-antigen complex
130
what does T helper cell activation require?
antigen-presenting cell
131
what happens after T helper cell is activated?
Th cell divides
132
what do Th cells divide into?
Th cells specific to same antigen
| memory Th cells
133
what do Th cells secrete?
cytokines that stimulate both cell-mediated and antibody-mediated immune responses
134
cytokines
signaling molecules used by immune cells
135
how can cytokines act?
locally and/or systematically
approx 20 are well characterized
perennial research targets for biological therapies
136
cytokines worth knowing
```
interleukin 1 (IL-1)
interleukin 2 (IL-2, T cell growth factor)
interleukin 5
interleukin 8
interferons
tumor necrosis factor (TNF, cachectin)
```
137
what is interleukin 1 IL-1 produced by?
produced by macrophages that are eating
138
what does interleukin 1 IL-1 do?
causes T cell division
causes increase in circulating neutrophils
causes the acute phase reaction
acts on the hypothalamus to cause fever and fatigue
attracts macrophages for granuloma formation
139
what is interleukin 2 (IL-2, T cell growth factor) produced by?
activated Th cells
140
what does interleukin 2 (IL-2, T cell growth factor) do?
causes T cell division
141
what is interleukin 5 produced by?
activated Th cells
142
what does interleukin 5 do?
causes increase in eosinophils-important in allergies and parasitic infestations
143
what is interleukin 8 produced by?
macrophages
144
what does interleukin 8 do?
chemotactic for neutrophils
145
what are interferons produced by?
some are produced by T cells
146
what do interferons do?
"interfere" with viruses and many other activities
147
what does beta interferon do?
transforms B cells into plasma cells
148
what does gamma interferon do?
activates macrophages and increases MHC II expression
149
what is tumor necrosis factor (TNF, cachectin) produced by?
produced by T cells, macrophages
150
what does tumor necrosis factor (TNF, cachectin) do?
causes inflammation
causes the acute phase reaction
acts on the hypothalamus to cause fever
induces apoptosis
151
what happens in B cell sensitization in antibody mediated immunity?
inactive B cells "sensitized" by binding of BCR to antigen
antigen taken into B cell
antigen expressed on B cell surface with MHC II
now recognizable by Th cell
152
what happens when Th cell binds in antibody mediated immunity?
Th cell binds to MHC-II-antigen complex
| secrete cytokines that "activate" B cell
153
what happens once B cell is activated?
activated B cell clones
154
what does an activated B cell clone into?
plasma cells
| memory B cells
155
what do plasma cells do?
produce and secrete antibodies
156
what do memory B cells do?
stay in circulation
| immediately form plasma cells if same antigen reencountered
157
what are antibodies (immunoglobulins)?
soluble proteins in plasma
158
what are antibodies (immunoglobulins) made of?
two pairs of amino acid chains
| heavy and light
159
what does each chain on an antibody consist of?
constant and variable segments
160
antibody (immunoglobulin) constant segments
```
determine Ig class
5 classes
```
161
antibody (immunoglobulin) variable segments
determine Ig specificity to antigen
| Antigen-binding site
162
IgM
first antibody secreted after B cell activation
short-lived
circulate as five-antibody starburst (pentamer)
responsible for rapid destruction of incompatible blood types
163
IgG
second antibody secreted after B cell activation
80% of plasma antibodies
long-lasting, monomer
responsible for resistance against many pathogens and toxins
164
can IgG cross placenta?
yes
| maternal IgG provies passive immunity to fetus and newborn
165
IgA
produced as dimer
found primarily in glandular secretions
glandular cells absorb from plasma and secrete them onto apical surface
bind pathogens before they enter body
166
what kinds of glandular secretions are IgA found in?
mucus, tears, saliva, breast milk
167
IgD
acts as B cell receptor
| binding of antigen sensitizes B cell
168
IgE
on surfaces of basophils and mast cells
Ag binding stimulates release of histamine to initiate inflammation
also important in allergic response
169
actions of antibodies
```
precipitation and agglutination
-formation of immune complexes
activation of complement system
stimulation of phagocytes
-opsonization
inciting inflammation
prevention of bacterial and viral adhesion
```
170
first antigen exposure
```
produces primary response
develops slowly, transient
-illness occurs
-antigens activate B cells to form plasma cells
-antibody production slow
```
171
subsequent antigen exposures
produces secondary response
more rapid, extensive and prolonged
no illness
memory cells already primed
