Unit 6 - Immune System Flashcards
1
Q
What is immunity?
A
ability of the body to fight off invaders and to protect itself
2
Q
What are the major functions of the immune system?
A
- Protect the body
- Remove dead/damaged tissue and cells
- Tries to recognize and remove abnormal cells
3
Q
What does the body protect you against?
A
- microbes = bacteria, viruses, fungi, protozoa
- parasites = worms, etc
- toxins produced by microbes
- other foreign proteins or substances (eg allergens)
4
Q
What happens when your immune system doesn’t perform normally?
A
- Incorrect responses = autoimmunity (attacks the body’s own tissues/organs)
- Overactive responses = allergies
- Lack of response = immunodeficiency (failure of the immune system to protect the body)
5
Q
What are pathogens?
A
disease-causing agents
6
Q
What are the different types of pathogens?
A
- Bacteria
- Viruses
7
Q
Where can bacteria be located?
A
can be intracellular and extracellular
8
Q
What is bacteria?
A
cells surrounded by a cell membrane and usually a cell wall
- they can survive and reproduce outside host
9
Q
Can bacteria be killed by drugs/antibiotics?
A
yes
10
Q
Where are viruses located?
A
intracellular
11
Q
What are viruses?
A
not cells, they have a nucleic acid core with a protein coat
- some have envelope derived from host cell membrane
- cannot reproduce alone
12
Q
Can viruses be killed by antibiotics?
A
no
13
Q
How do you treat viruses?
A
antiviral drugs
14
Q
How does viruses reproduce?
A
once they are inside the host, the nucleic acid takes over, and then new viral particles either rupture host cell or they bud off from host cell
15
Q
Why are immune system organs called lymphoid organs?
A
because lymphocytes are found there
16
Q
How are lymphoid organs connected?
A
by blood vessels and the lymph vessels
17
Q
What do lymphoid organs carry?
A
carry lymph
18
Q
What is lymph?
A
clear fluid, essentially extracellular fluid, that has left capillaries and filter through tissue
- lymph is a conduit for immunologically active cells to travel through
19
Q
What are lymph nodes?
A
bean-shaped nodes that are located at strategic positions
20
Q
Where are lymph nodes located?
A
knee, groin, elbow, shoulder, neck
21
Q
What is periphery?
A
regions of the body outside lymphoid organs
22
Q
What are the two types of lymphoid organs?
A
- Primary Lymphoid organs
- Secondary Lymphoid organs
23
Q
What do primary lymphoid organs do?
A
organ. where lymphocytes develop (form and mature)
24
Q
What are the two primary lymphoid organs?
A
- bone marrow
- thymus
25
What happens at the bone marrow?
all blood cells originate here
26
What type of cells mature at bone marrow?
B lymphocytes mature here
27
What type of cells mature at the thymus?
T lymphocytes mature here
28
What do secondary lymphoid organs do?
organs where lymphocytes, mature immune cells, interact with pathogens and initiate a response
29
What are examples of secondary lymphoid organs?
spleen, lymph nodes, tonsils, and Gut Associated Lymphoid Tissue (GALT)
30
What does secondary lymphoid organs filter?
filter blood and lymphs for pathogens or pathogen containing lymphocytes
31
What do afferent lymph vessels do?
bring in lymphocytes from periphery (regions of body outside lymphoid organs)
32
What do efferent lymph vessels do?
allows the lymphocytes to keep circulating
33
What does pulp in lymph node do?
allows mixing of lymphocytes and other leukocytes (white blood cells)
34
What do arteries and veins supply?
supply nutrients and oxygen, and non-lymphocytic leukocytes ("non-immune cell WBCs")
35
What are the two encapsulated lymphoid tissues?
1. spleen
2. lymph nodes
- they have a fibrous wall
36
What are the two unencapsulated lymphoid tissues?
1. tonsils
2. GALT (gut associated lymphoid tissue)
- they diffuse
37
What are leukocytes?
aka white blood cells, they're the primary cell type responsible for immune responses
38
Size comparison of RBCs vs WBCs
WBCs are larger than RBCs but less in number
39
What are WBCs/leukocytes able to do?
they circulate in the blood but they also leave the blood stream and function extravascularly (outside the vessels)
40
What are the lifespans of leukocytes?
ranging from few hours to several months
41
What are the six main types of leukocytes?
1. Eosinophils
2. Basophils (Mast cells)
3. Neutrophils
4. Monocytes (Macrophages)
5. Lymphocytes
6. Dendritic cells
42
What are the types that leukocytes are divided into by their function?
1. Granulocytes
2. Phagocytes
3. Cytotoxin cells
4. antigen presenting cells (APCs)
43
What is granulocytes?
- white blood cells whose cytoplasm contains prominent granules (the granules have staining properties)
44
Which types of leukocytes are granulocytes?
eosinophils (stain), basophils (stain), neutrophils (neutral, no stain)
45
What is phagocytes?
- engulf and ingest pathogens
46
What types of leukocytes are phagocytes?
neutrophils, macrophages, dendritic cells
47
What is cytotoxin cells?
- kill other cells, even self-cells
48
What types of leukocytes are cytotoxin cells?
eosinophils, and some lymphocytes
49
What is antigen presenting cells (APCs)?
- ability to display fragments of pathogens on cell surface as a signal to other immune cells
50
What types of leukocytes are APCs?
some lymphocytes, dendritic cells, macrophages
51
What are antigen and antibodies?
antigen (Ag): substances that are recognized by an antibody and induces an immune response
antibodies (Ab): proteins that bind to Ag's and target pathogens for destruction
52
What are eosinophils?
cytotoxic granulocytes with bright pink staining granules
53
What is the role of eosinophils?
role in defense against parasites and and function in allergic response
54
How long do eosinophils live for?
6-12 hours; thus very few in peripheral circulation
55
Where are eosinophils located?
digestive tract, lungs, genital tract, skin
56
How do eosinophils respond?
they respond by binding to an antibody-coated parasite and degranulate by spewing granule contents
- the granule contents (toxic enzymes and oxidative chemicals) damage and kill the parasites (cytotoxic)
57
How are eosinophils involved in allergic reactions?
they contribute to inflammation and tissue damage by releasing toxic enzymes and oxidative substances
58
What are basophils?
granulocytes involved in allergic responses, and have large dark blue staining granules
59
Is there a lot of basophils in blood?
no, it is rare in numbers
60
Where are basophils found?
like mast cells in tissues, they are found in digestive tract, lungs, skin
61
Where are basophils found?
like mast cells in tissues, they are found in the digestive tract, lungs, skin
62
What do granules in basophils contain?
histamine, heparin, cytokines
63
How are basophils involved in allergic responses?
degranulate; releasing the toxic enzymes/oxidative chemicals causes inflammation and tissue damage
64
What are neutrophils?
granulocytes that are phagocytic
65
How long do neutrophils live for?
1-2 days
66
How many bacterias can neutrophils ingest?
5-20 bacteria
67
Can neutrophils leave the circulatory system?
yes, they can leave the circulatory system to attack pathogens in tissues
68
What do the granules in neutrophils contain?
contains cytokines that cause fever and start other inflammatory responses
69
How many neutrophils are there?
it is the most abundant leukocyte (50-70% of total leukocytes)
70
What are monocytes?
monocytes are precursor cells of tissue macrophages
71
How many monocytes are there?
uncommon in blood (1-6% in total leukocytes)
72
How long do monocytes stay in the blood?
8 hours, then they move into tissues to become macrophages
73
What are macrophages?
large amoeboid cells and functions as scavengers by phagocytosing old red blood cells and dead neutrophils
74
How much bacteria an it ingest/phagocytose?
up to 100 bacteria
75
What is the role of monocytes in adaptive immune response?
the phagocytosed pathogens are digested and fragments are placed on the cell surface (APCs)
76
What are lymphocytes?
key players in the adaptive immune response
77
How many lymphocytes are there?
make up 20-30% of total leukocytes
78
How many lymphocytes are in the circulation?
only 5%; most are found in lymphoid tissues (where they are likely to encounter invaders)
79
How many lymphocytes are present in an adult body at any one time?
10^12; one trillion
80
How does lymphocytes look under the microscope?
all look alike, but they have fundamental differences in function
81
What are dendritic cells?
phagocytic antigen presenting cells (APCs)
82
Where are dendritic cells found?
in skin and other organs
83
How do dendritic cells function?
they recognize and engulf pathogens, and then digest the pathogens and place them on the cell surface. then the "activated" cells migrate to secondary lymphoid organs to present the antigens to lymphocytes
84
What is haematopoiesis?
- all blood cells are produced in the bone marrow
- derived from pluripotent haematopoietic stem cells
- give rise to uncommitted stem cells (still capable of many fates)
- uncommitted stem cells give rise to commented progenitor cells (develop into each cell type)
- the path taken is guided by cytokines
85
Where are B lymphocytes (B cells) produced?
bone marrow
86
Where do B lymphocytes/B cells mature/develop?
mature/develop in the Bursa of Fabricius (an invagination of the colon)
87
Do mammals have a bursa?
no
88
What do B lymphocytes/B cells produce?
produce antibodies
89
Where are the antibodies produced by B lymphocytes/B cells found?
can be found on the cell surface as receptors or free Ab's in the plasma
90
Where are T lymphocytes/T cells produced?
they are produced in the bone marrow
91
Where do T lymphocytes mature/develop?
mature/develop in the thymus
92
How does T lymphocytes communicate?
use contact-dependent signalling (cell-to-cell communication) via the T-cell receptor expressed on the T cell membrane
93
What can T-cell receptors bind to?
only bind to MHC-antigen complexes (cannot bind to free Ag)
94
What does MHC stand for?
stands for Major Histocompatibility Complex
95
What are MHCs?
proteins that are expressed on the surface of cells that display "self-antigens" and "non-self-antigens" to T cells
96
What are the two classes of MHC that interact with T cells?
1. Class I (on all nucleated cells)
2. Class II (on APCs)
97
What are the subtypes of T cells?
1. Cytotoxic T cells (Tc) or killer T cells
2. Helper T cells (Th)
3. Regulatory T cells (Tregs)
98
What are the functions of cytotoxic T cells (killer T cells)?
- recognizes Ag presented on Class I MHC
- kills cell that expresses appropriate Ag
99
What are the functions of helper T cells?
- recognize Ag presented on Class II MHC
- promote differentiation of B cells and Tc cells and can activate macrophages
100
What are the functions of regulatory T cells (T regs)?
- recognize Ag presented on Class II MHC
- suppress other immune cells to prevent excessive immune responses
101
When do immune responses take over?
when pathogens overcome the defense system of the body (physical, chemical, and mechanical barriers eg. skin, tears, mucus, stomach acid)
102
What are the steps the body initiates for an immune response?
1. Detection and identification of foreign substance
2. Communication with other immune cells
3. Recruitment of help and co-ordination of the response
4. Destruction or suppression of the invader
103
What do immune systems use to communicate?
chemical signalling (cell-to-cell communication)
104
What are the two types of chemical signalling used in immune system?
1. Antibodies (Ab)
2. Cytokines
105
What are antibodies (Ab)?
bind to antigen (Ag) as a signal
106
What are cytokines?
affect growth or activity of other cells
107
What are the two categories of immunity?
1. innate immunity
2. adaptive immunity
108
What is the response time for innate and adaptive immunity?
innate is more rapid, less specific response
adaptive response is slower, more specific
109
Can innate responses lead to adaptive responses?
yes
110
What is innate immunity?
it is present before pathogen is encountered and is non-specific; it's the body's immediate immune response to invasion
111
How long does it take for innate immunity to respond?
response begins within minutes to hours and it does not remember past infections
112
What is a sign of innate immunity?
inflammation: visible on the skin as a red, warm, swollen area
113
Do all organisms have innate immunity?
yes
114
What is adaptive immunity?
directed at specific invaders and is the body's specific immune response
115
When does adaptive immunity develop?
after the pathogen is encountered
116
How long does it take adaptive immunity to respond?
days to weeks, but it remembers past infections
117
Where is adaptive immunity found?
in vertebrates only
118
What is adaptive immunity divided into?
1. cell-mediated immunity
2. antibody-mediated immunity (humoral immunity)
119
What is the role of innate immunity?
- provide clearance of pathogens or containment of the pathogen until adaptive response kicks in
- physical and chemical barriers provide the first line of defense
- second line of defense are patrolling or stationary leukocytes and blood proteins
120
What is the first line of defense for innate immunity?
physical barriers (eg. skin, mucous linings of the gut and genital tract, and ciliated epithelium of respiratory system) and chemical barriers (eg. stomach acids)
- very vulnerable because the epithelium is thin and exposed to outside environment
121
What type of cells are innate immune system cells?
majority are phagocytes which destroy or suppress the invader by ingesting it
122
What do innate immune system cells do to attract other cells?
secrete cytokines
123
What is chemotaxins?
chemicals that attract other immune cells eg. cytokines
124
What is extravasion?
when phagocytes leave the circulation and enter tissue through capillary walls
125
How do phagocytes identify the invader?
by chemical cues which interacts with receptors on the phagocytes membrane
126
How does the phagocyte engulf the invader?
- the receptors bind sequentially to allow the phagocytes to engulf the invader
- movement of the pseudopodia is aided by actin filaments to push the cell around the invader
127
What kinds of materials can be ingested by the phagocytes?
organic and inorganic materials
128
What are opsonin and what do they do?
some pathogens do not have surface features that can be recognized directly by the phagocytes, so opsonin, a blood protein, binds to it and coats the pathogen; phagocytes have receptors for opsonin so they will be able to identify if and engulf it
129
What is a phagosome?
the foreign particle captured by phagocytosis in a vesicle after ingestion
130
What is a phagolysosome?
the fusion of a phagosome and lysosomes which contain enzyme and chemicals that kill the pathogen
131
What is pus?
dead phagocytes, tissue fluids, and debris collect at the site of injury
132
What are natural killer cells (NK)?
lymphocytes (WBCs) associated with innate immunity; however, lymphocytes are generally associated with adaptive responses
133
How long does it take NK cells to respond?
NK cells act within minutes and they do not have specific receptors as seen in B cells and T cells
134
What do NK cells bring?
they bring about apoptosis (programmed cell death) in pathogen-infected cells; they also attack tumour cells
135
What do NK cells produce?
important cytokines:
1. interferons
2. IFN alpha and beta
3. IFN gamma
136
What is interferons?
cytokines that interfere with viral replication
137
What are IFN alpha and beta?
cytokines that induces an "antiviral state" in nearby cells that prevents viral replication
138
What are IFN gamma?
cytokines that activates macrophages and other immune cells
139
What is the role of chemical mediators?
they play a role in the innate response
140
What do chemical mediators create?
inflammatory response: red warm swelling in the skin is hallmark of innate response
141
What does inflammatory response do?
serve as a signal to attract other cells and chemical agents to the site
142
What happens during inflammation?
- increased capillary permeability and causes fever
- produces a physical barrier that prevents the spread of pathogen
- tissue repair is promoted
143
What causes the chemical mediators' response?
cytokines that are released by macrophages
- Interleukin-1 (IL-1) mediates most of the effects
- the effects are mainly local, but can be systemic
144
What is Interleukin-1?
mainly made by macrophage (WBC), and helps leukocytes (WBC) fight infections
145
What is the function of Interleukin-1?
1. Act on endothelial cells lining the blood vessels (loosens junctions between cells)
2. Act on liver cells to produce blood proteins involved in damage control
3. Induce fever
4. Stimulate cytokine production
146
What is complement proteins?
take parts in innate response, complement is a collective term for over 25 blood proteins (some are opsonins, some are chemotaxins)
147
How are complement proteins activated?
by sequential proteolysis
148
What is Membrane Attack Complex (Mac attack)?
complement proteins that make holes in pathogen membranes, which allows ions to enter; where ions go, water follows, pathogen swells and lyses (cell membrane is destroyed)
149
What are adaptive immunity also called?
acquired or specific immunity
150
How do adaptive immunity start?
products of innate immune responses start the acquire responses
151
What is involved in adaptive immunity?
lymphocytes and lymphocyte products
152
What types of lymphocytes are involved in adaptive immunity?
1. B cells
- activated form = plasma cell
2. T cells
- Tc and Th and Tregs
153
What do all lymphocytes produce?
cytokines
154
What is specificity?
each individual cell recognizes a different specific pathogen
155
What expands clonally?
T cells and B cells (able to make identical copies of itself)
156
How many different B and T cells do we have?
millions; but we only have a few naive cells
157
What are naive cells?
cells that have never encountered their specific antigen (no pathogen exposure)
158
What are the steps for adaptive immune system cells?
the recognize a pathogen, expand clonally, and produce many effector cells which attack the pathogen; some cells become memory cells
159
What are memory cells?
cells that respond faster than naive cells; they stick around longer and continue to reproduce, if pathogen comes back, it's easier to find clone
160
What is humoral immunity?
B cells produce antibodies that take part in antibody-mediating immunity
161
What is another term for antibodies?
immunoglobulins
162
Where are antibodies/immunoglobulins found?
either a cell membrane protein of B lymphocytes or secreted by B lymphocytes
163
What can membrane Ab's be used for?
as markers to identify each different clone of B cells
164
What happens when B cells are stimulated?
they mature into plasma cells
165
What are plasma cells?
mature B cells that produce ~2000 antibody molecules per second
166
How long do plasma cells live for?
they are short lived and die after response is over; a few memory cells survive (they remember the past infection)
167
When do antibodies respond?
after the first and second exposure to an antigen
168
When does primary Ab response happen?
on the first exposure to an antigen; there is a slower and delayed response and less antibody concentration
169
When does secondary Ab response happen?
on the second exposure to an antigen; response is much faster, more antibodies produced
170
Why does secondary Ab response faster?
because mediated by memory cells; this is the principle of why vaccination works
171
How does vaccination work?
patient is given an inactivated or partial pathogen and then generate memory cells so that if they're affected, the memory cells recognize the natural pathogen
172
What are the 5 classes of immunoglobulins (Ig)? (MADGE)
1. IgM
2. IgA
3. IgD
4. IgG
5. IgE
173
What is IgM?
immunoglobulin produced during primary responses which activates complement
174
What is IgA?
immunoglobulins found in external secretions (eg. saliva, tears); they neutralize (bind to pathogens and flag them for phagocytosis) pathogens before entry into internal environment
175
What is IgD?
found on surface of B cells with IgM (function is unknown)
176
What is IgG?
make up 75% of plasma antibodies in adults, secondary response antibody (activates complement, opsonizes)
177
What is IgE?
associated with allergic responses and are recognized by mast cells
178
What is the structure of an antibody?
- four polypeptides linked into a Y shape with 2 light chains and 2 heavy chains
- each side of the Y is identical - one light chain linked to one heavy chain
- the arms (Fab) contain the antigen binding sites
- the stem (Fc) determines which of the five classes an antibody belongs to
- there is a hinge between the Fab and Fc portions
179
What are the funcions of antigens?
1. Act as opsonins to tag Ag's for phagocytosis
2. Cause antigen/pathogen clumping
3. Neutralize bacterial toxins
4. Activate complement
5. Activate B cells
6. Activate Ab-dependent cellular activity (eg. activate Nk cells or eosinophils)
7. Activate mast cells to degranulate
180
How much do antibodies make up of proteins found in plasma?
20%
181
What are antibodies most effect against?
they are most effective against extracellular pathogens before they invade a cell
- also effective against macrobolecules
182
Does antibodies damage the pathogens?
no, they make pathogens more visible to immune defenses or activate defenses
183
How do antibodies bind?
- B cells have antibodies on their surface as receptors that can bind. antigen directly
- other cells use Fc receptors which interact and bind with the Fc region of the Ab
184
What do T-cells do in adaptive immunity?
they mediate cellular immunity
185
What do T cells need to be in?
direct contact with the target cell expressing an antigen
186
What is a T cell receptor?
an antigen specific molecule that is expressed only as a cell-surface protein; it detects Ag presented on the surface of. target cell via the MHC receptor
187
Can T cell receptors bind to free antigen?
no, must bind to antigen displayed on Class I or II MHC
188
What are the two types of MHC proteins?
1. Class I MHC
2. Class II MHC
189
What is Class I MHC?
present on the surface of every nucleated (every cell with a nucleus) cell in the body
190
What does the Class I MHC do?
defend against pathogens that get inside cells
- peptides are present in MHC Class I to cytotoxic T (Tc) cells
- Tc cells kill the cells that express the peptides
191
What does Class I MHC proteins release?
- perforin: forms pores in target cell
- granzymes: enters through the pores and triggers apoptosis
192
What is Class II MHC?
present on the surface of specialized immune system cells (antigen presenting cells APCs)
193
What do Class II MHC proteins do?
the cells respond to extracellular pathogens and they present peptides in MHC class II to helper T (Th) cells or Regulatory T (Treg) cells
- the Th cells respond by secreting cytokines that activate other immune system cells
- the Treg cells respond by secreting cytokines that suppress other immune system cells
194
What are the 4 types of immune responses?
1. Extracellular bacteria
2. Intracellular viruses
3. Allergic responses
4. Foreign tissue
195
Which response starts first, innate or adaptive?
innate response starts first then adaptive response
196
What is the result of a bacterial invasion?
results in an inflammatory response, includes redness, welling, tenderness
197
What are the stages of a bacterial invasion response?
1. Complement proteins are activated by bacterial cell wall components
2. Haemostasis occurs if a blood vessel is broken
3. Phagocytes produce cytokines and activated lymphocytes present antigens
4. Cytokines secreted by Th cells activate B cells
5. B cells clonally expand, becoming plasma cells that produce antibodies that act as opsonins and activate complement
6. End of response most lymphocytes die but some become memory cells
198
What are the stages of a bacterial invasion response?
1. Complement proteins are activated by bacterial cell wall components
- some act as chemotaxins and attract leukocytes from circulation
- some form "MAC" attack and lyse bacteria
- some opsonize bacteria, helping phagocytes digest encapsulated ones
2. Haemostasis occurs if a blood vessel is broken (site of injury)
3. Phagocytes produce cytokines and activated lymphocytes present antigens
4. Cytokines secreted by Th cells activate B cells
5. B cells clonally expand, becoming plasma cells that produce antibodies that act as opsonins and activate complement
6. End of the response most lymphocytes die but some become memory cells
199
What works together to destroy the virus and virus-infected cells?
T-cell mediated and humoral immunity
200
What do viruses have to go through before they infect a host?
they have to first go through an extracellular phase; phagocytes and Ab's help to opsonize and neutralize here
201
What are the stages of response to viral infection?
1. once the virus is intracellular, most immune cells and antibodies can't get at them
2. infected host cells produce IFN beta and macrophages produce IFN alpha (this induces an antiviral state in nearby cells)
3. cytokines are secreted from host cells and macrophages activate NK and Tc cells
4. Tc cells recognize viral peptides in MHC class I of infected cell and kill it (perforin, granzymes, and fas ligand induce apoptosis in target cell)
5. some viruses turn off MHC class I expression on infected host cell (NK cells kill any cell with no MHC class I on its surface)
6. end of response most Tc cells die but some become memory cells
202
What are allergies?
an inflammatory immune response to. anon-pathogenic antigen
203
What are the inflammatory responses in allergies triggered by?
triggered by specific antigens that cause allergies (allergens) which are not harmful by themselves; allergens can be inhaled, ingested, or touched, and can be practically any foreign substance (organic, non-organic, synthetic, or natural), they are also generally low molecular weight and low concentration
204
What individuals develop inflammatory responses to allergens?
sensitive (atopic) individuals, and the resulting response is worse and causes more damage than the antigen; the range vaires from vild to fatal
205
What are allergic responses?
hypersensitivities
206
What are the two types of hypersensitivities?
1. Immediate hypersensitivities; happens in minutes and are antibody mediated
2. Delayed type hypersensitivity (DTH); takes hours to days and are mediated by T cells and macrophages
207
What are the steps of response in an immediate hypersensitivity response (happens in minutes, Ab mediated)?
1. Sensitization phase:
- equivalent to primary immune response
- antigen is ingested by APC (activates Th cells)
- Th cell activates B cell to make IgE antibody class
- Th cell and B cell become memory cells
2. Re-exposure:
- equivalent to secondary response (body reacts strongly and rapidly)
- generally, IgE on mast cells detects allergen
- mast cells degranulate releasing cytokines and histamines (results in an inflammatory reaction)
208
What is the two types of severity of allergic responses?
1. Localized (rashes or hay fever)
2. Systemic (anaphylactic shock)
209
What happens during a systemic allergic response?
- widespread vasodilation, circulatory collapse
- bronchoconstriction
210
How can you transplant foreign tissues not be ejected by the recipient's immune system?
- MHC proteins are primary tissue antigens that must be recognized as foreign
- MHC proteins are also called Human leukocyte Antigens (HLA)
- if the recipient and donor share the same HLA the tissue is often transplanted successfully
211
What are the two possible outcomes of the transplant?
i. rejection of the host by the donor tissue (graft vs. host)
ii. rejection of the donor tissue by the recipient's immune system (host vs graft)
212
What is a common example of tissue donation?
blood transfusion; they don't contain MHC proteins found on nucleated cells
213
The blood groups have four blood types:
Type O, A, B, and AB
214
What happens when the wrong blood type is introduced into the recipient?
the antibodies react and the cells clump (agglutinate)
215
What does antibody binding activate?
complement proteins
- MAC attack, cells lyse and Hb (hemoglobin) released
- free Hb causes acute renal failure because kidneys try to filter blood with large molecules
216
When do people express antibodies to RBCs?
people express antibodies to the red blood cell antigen that they do not process
Type O: anti-A and anti-B antibodies
Type A: anti-B antibodies
Type B: anti-A antibodies
Type AB: no antibodies
