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BIOL273 > Unit 6 - Immune System > Flashcards

Unit 6 - Immune System Flashcards

1
Q

What is immunity?

A

ability of the body to fight off invaders and to protect itself

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2
Q

What are the major functions of the immune system?

A
  1. Protect the body
  2. Remove dead/damaged tissue and cells
  3. Tries to recognize and remove abnormal cells
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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)
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4
Q

What happens when your immune system doesn’t perform normally?

A
  1. Incorrect responses = autoimmunity (attacks the body’s own tissues/organs)
  2. Overactive responses = allergies
  3. Lack of response = immunodeficiency (failure of the immune system to protect the body)
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5
Q

What are pathogens?

A

disease-causing agents

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6
Q

What are the different types of pathogens?

A
  1. Bacteria
  2. Viruses
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7
Q

Where can bacteria be located?

A

can be intracellular and extracellular

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8
Q

What is bacteria?

A

cells surrounded by a cell membrane and usually a cell wall
- they can survive and reproduce outside host

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9
Q

Can bacteria be killed by drugs/antibiotics?

A

yes

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10
Q

Where are viruses located?

A

intracellular

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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

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12
Q

Can viruses be killed by antibiotics?

A

no

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13
Q

How do you treat viruses?

A

antiviral drugs

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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

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15
Q

Why are immune system organs called lymphoid organs?

A

because lymphocytes are found there

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16
Q

How are lymphoid organs connected?

A

by blood vessels and the lymph vessels

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17
Q

What do lymphoid organs carry?

A

carry lymph

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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

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19
Q

What are lymph nodes?

A

bean-shaped nodes that are located at strategic positions

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20
Q

Where are lymph nodes located?

A

knee, groin, elbow, shoulder, neck

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21
Q

What is periphery?

A

regions of the body outside lymphoid organs

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22
Q

What are the two types of lymphoid organs?

A
  1. Primary Lymphoid organs
  2. Secondary Lymphoid organs
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23
Q

What do primary lymphoid organs do?

A

organ. where lymphocytes develop (form and mature)

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24
Q

What are the two primary lymphoid organs?

A
  1. bone marrow
  2. thymus
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25
Q

What happens at the bone marrow?

A

all blood cells originate here

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26
Q

What type of cells mature at bone marrow?

A

B lymphocytes mature here

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27
Q

What type of cells mature at the thymus?

A

T lymphocytes mature here

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28
Q

What do secondary lymphoid organs do?

A

organs where lymphocytes, mature immune cells, interact with pathogens and initiate a response

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29
Q

What are examples of secondary lymphoid organs?

A

spleen, lymph nodes, tonsils, and Gut Associated Lymphoid Tissue (GALT)

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30
Q

What does secondary lymphoid organs filter?

A

filter blood and lymphs for pathogens or pathogen containing lymphocytes

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31
Q

What do afferent lymph vessels do?

A

bring in lymphocytes from periphery (regions of body outside lymphoid organs)

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32
Q

What do efferent lymph vessels do?

A

allows the lymphocytes to keep circulating

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33
Q

What does pulp in lymph node do?

A

allows mixing of lymphocytes and other leukocytes (white blood cells)

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34
Q

What do arteries and veins supply?

A

supply nutrients and oxygen, and non-lymphocytic leukocytes (“non-immune cell WBCs”)

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35
Q

What are the two encapsulated lymphoid tissues?

A
  1. spleen
  2. lymph nodes
    - they have a fibrous wall
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36
Q

What are the two unencapsulated lymphoid tissues?

A
  1. tonsils
  2. GALT (gut associated lymphoid tissue)
    - they diffuse
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37
Q

What are leukocytes?

A

aka white blood cells, they’re the primary cell type responsible for immune responses

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38
Q

Size comparison of RBCs vs WBCs

A

WBCs are larger than RBCs but less in number

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39
Q

What are WBCs/leukocytes able to do?

A

they circulate in the blood but they also leave the blood stream and function extravascularly (outside the vessels)

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40
Q

What are the lifespans of leukocytes?

A

ranging from few hours to several months

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41
Q

What are the six main types of leukocytes?

A
  1. Eosinophils
  2. Basophils (Mast cells)
  3. Neutrophils
  4. Monocytes (Macrophages)
  5. Lymphocytes
  6. Dendritic cells
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42
Q

What are the types that leukocytes are divided into by their function?

A
  1. Granulocytes
  2. Phagocytes
  3. Cytotoxin cells
  4. antigen presenting cells (APCs)
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43
Q

What is granulocytes?

A
  • white blood cells whose cytoplasm contains prominent granules (the granules have staining properties)
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44
Q

Which types of leukocytes are granulocytes?

A

eosinophils (stain), basophils (stain), neutrophils (neutral, no stain)

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45
Q

What is phagocytes?

A
  • engulf and ingest pathogens
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46
Q

What types of leukocytes are phagocytes?

A

neutrophils, macrophages, dendritic cells

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47
Q

What is cytotoxin cells?

A
  • kill other cells, even self-cells
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48
Q

What types of leukocytes are cytotoxin cells?

A

eosinophils, and some lymphocytes

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49
Q

What is antigen presenting cells (APCs)?

A
  • ability to display fragments of pathogens on cell surface as a signal to other immune cells
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50
Q

What types of leukocytes are APCs?

A

some lymphocytes, dendritic cells, macrophages

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51
Q

What are antigen and antibodies?

A

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

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52
Q

What are eosinophils?

A

cytotoxic granulocytes with bright pink staining granules

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53
Q

What is the role of eosinophils?

A

role in defense against parasites and and function in allergic response

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54
Q

How long do eosinophils live for?

A

6-12 hours; thus very few in peripheral circulation

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55
Q

Where are eosinophils located?

A

digestive tract, lungs, genital tract, skin

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56
Q

How do eosinophils respond?

A

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)

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57
Q

How are eosinophils involved in allergic reactions?

A

they contribute to inflammation and tissue damage by releasing toxic enzymes and oxidative substances

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58
Q

What are basophils?

A

granulocytes involved in allergic responses, and have large dark blue staining granules

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59
Q

Is there a lot of basophils in blood?

A

no, it is rare in numbers

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60
Q

Where are basophils found?

A

like mast cells in tissues, they are found in digestive tract, lungs, skin

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61
Q

Where are basophils found?

A

like mast cells in tissues, they are found in the digestive tract, lungs, skin

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62
Q

What do granules in basophils contain?

A

histamine, heparin, cytokines

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63
Q

How are basophils involved in allergic responses?

A

degranulate; releasing the toxic enzymes/oxidative chemicals causes inflammation and tissue damage

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64
Q

What are neutrophils?

A

granulocytes that are phagocytic

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65
Q

How long do neutrophils live for?

A

1-2 days

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66
Q

How many bacterias can neutrophils ingest?

A

5-20 bacteria

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67
Q

Can neutrophils leave the circulatory system?

A

yes, they can leave the circulatory system to attack pathogens in tissues

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68
Q

What do the granules in neutrophils contain?

A

contains cytokines that cause fever and start other inflammatory responses

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69
Q

How many neutrophils are there?

A

it is the most abundant leukocyte (50-70% of total leukocytes)

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70
Q

What are monocytes?

A

monocytes are precursor cells of tissue macrophages

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71
Q

How many monocytes are there?

A

uncommon in blood (1-6% in total leukocytes)

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72
Q

How long do monocytes stay in the blood?

A

8 hours, then they move into tissues to become macrophages

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73
Q

What are macrophages?

A

large amoeboid cells and functions as scavengers by phagocytosing old red blood cells and dead neutrophils

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74
Q

How much bacteria an it ingest/phagocytose?

A

up to 100 bacteria

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75
Q

What is the role of monocytes in adaptive immune response?

A

the phagocytosed pathogens are digested and fragments are placed on the cell surface (APCs)

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76
Q

What are lymphocytes?

A

key players in the adaptive immune response

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77
Q

How many lymphocytes are there?

A

make up 20-30% of total leukocytes

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78
Q

How many lymphocytes are in the circulation?

A

only 5%; most are found in lymphoid tissues (where they are likely to encounter invaders)

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79
Q

How many lymphocytes are present in an adult body at any one time?

A

10^12; one trillion

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80
Q

How does lymphocytes look under the microscope?

A

all look alike, but they have fundamental differences in function

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81
Q

What are dendritic cells?

A

phagocytic antigen presenting cells (APCs)

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82
Q

Where are dendritic cells found?

A

in skin and other organs

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83
Q

How do dendritic cells function?

A

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

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84
Q

What is haematopoiesis?

A
  • 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
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85
Q

Where are B lymphocytes (B cells) produced?

A

bone marrow

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86
Q

Where do B lymphocytes/B cells mature/develop?

A

mature/develop in the Bursa of Fabricius (an invagination of the colon)

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87
Q

Do mammals have a bursa?

A

no

88
Q

What do B lymphocytes/B cells produce?

A

produce antibodies

89
Q

Where are the antibodies produced by B lymphocytes/B cells found?

A

can be found on the cell surface as receptors or free Ab’s in the plasma

90
Q

Where are T lymphocytes/T cells produced?

A

they are produced in the bone marrow

91
Q

Where do T lymphocytes mature/develop?

A

mature/develop in the thymus

92
Q

How does T lymphocytes communicate?

A

use contact-dependent signalling (cell-to-cell communication) via the T-cell receptor expressed on the T cell membrane

93
Q

What can T-cell receptors bind to?

A

only bind to MHC-antigen complexes (cannot bind to free Ag)

94
Q

What does MHC stand for?

A

stands for Major Histocompatibility Complex

95
Q

What are MHCs?

A

proteins that are expressed on the surface of cells that display “self-antigens” and “non-self-antigens” to T cells

96
Q

What are the two classes of MHC that interact with T cells?

A
  1. Class I (on all nucleated cells)
  2. Class II (on APCs)
97
Q

What are the subtypes of T cells?

A
  1. Cytotoxic T cells (Tc) or killer T cells
  2. Helper T cells (Th)
  3. Regulatory T cells (Tregs)
98
Q

What are the functions of cytotoxic T cells (killer T cells)?

A
  • recognizes Ag presented on Class I MHC
  • kills cell that expresses appropriate Ag
99
Q

What are the functions of helper T cells?

A
  • recognize Ag presented on Class II MHC
  • promote differentiation of B cells and Tc cells and can activate macrophages
100
Q

What are the functions of regulatory T cells (T regs)?

A
  • recognize Ag presented on Class II MHC
  • suppress other immune cells to prevent excessive immune responses
101
Q

When do immune responses take over?

A

when pathogens overcome the defense system of the body (physical, chemical, and mechanical barriers eg. skin, tears, mucus, stomach acid)

102
Q

What are the steps the body initiates for an immune response?

A
  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
Q

What do immune systems use to communicate?

A

chemical signalling (cell-to-cell communication)

104
Q

What are the two types of chemical signalling used in immune system?

A
  1. Antibodies (Ab)
  2. Cytokines
105
Q

What are antibodies (Ab)?

A

bind to antigen (Ag) as a signal

106
Q

What are cytokines?

A

affect growth or activity of other cells

107
Q

What are the two categories of immunity?

A
  1. innate immunity
  2. adaptive immunity
108
Q

What is the response time for innate and adaptive immunity?

A

innate is more rapid, less specific response
adaptive response is slower, more specific

109
Q

Can innate responses lead to adaptive responses?

A

yes

110
Q

What is innate immunity?

A

it is present before pathogen is encountered and is non-specific; it’s the body’s immediate immune response to invasion

111
Q

How long does it take for innate immunity to respond?

A

response begins within minutes to hours and it does not remember past infections

112
Q

What is a sign of innate immunity?

A

inflammation: visible on the skin as a red, warm, swollen area

113
Q

Do all organisms have innate immunity?

A

yes

114
Q

What is adaptive immunity?

A

directed at specific invaders and is the body’s specific immune response

115
Q

When does adaptive immunity develop?

A

after the pathogen is encountered

116
Q

How long does it take adaptive immunity to respond?

A

days to weeks, but it remembers past infections

117
Q

Where is adaptive immunity found?

A

in vertebrates only

118
Q

What is adaptive immunity divided into?

A
  1. cell-mediated immunity
  2. antibody-mediated immunity (humoral immunity)
119
Q

What is the role of innate immunity?

A
  • 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
Q

What is the first line of defense for innate immunity?

A

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
Q

What type of cells are innate immune system cells?

A

majority are phagocytes which destroy or suppress the invader by ingesting it

122
Q

What do innate immune system cells do to attract other cells?

A

secrete cytokines

123
Q

What is chemotaxins?

A

chemicals that attract other immune cells eg. cytokines

124
Q

What is extravasion?

A

when phagocytes leave the circulation and enter tissue through capillary walls

125
Q

How do phagocytes identify the invader?

A

by chemical cues which interacts with receptors on the phagocytes membrane

126
Q

How does the phagocyte engulf the invader?

A
  • 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
Q

What kinds of materials can be ingested by the phagocytes?

A

organic and inorganic materials

128
Q

What are opsonin and what do they do?

A

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
Q

What is a phagosome?

A

the foreign particle captured by phagocytosis in a vesicle after ingestion

130
Q

What is a phagolysosome?

A

the fusion of a phagosome and lysosomes which contain enzyme and chemicals that kill the pathogen

131
Q

What is pus?

A

dead phagocytes, tissue fluids, and debris collect at the site of injury

132
Q

What are natural killer cells (NK)?

A

lymphocytes (WBCs) associated with innate immunity; however, lymphocytes are generally associated with adaptive responses

133
Q

How long does it take NK cells to respond?

A

NK cells act within minutes and they do not have specific receptors as seen in B cells and T cells

134
Q

What do NK cells bring?

A

they bring about apoptosis (programmed cell death) in pathogen-infected cells; they also attack tumour cells

135
Q

What do NK cells produce?

A

important cytokines:
1. interferons
2. IFN alpha and beta
3. IFN gamma

136
Q

What is interferons?

A

cytokines that interfere with viral replication

137
Q

What are IFN alpha and beta?

A

cytokines that induces an “antiviral state” in nearby cells that prevents viral replication

138
Q

What are IFN gamma?

A

cytokines that activates macrophages and other immune cells

139
Q

What is the role of chemical mediators?

A

they play a role in the innate response

140
Q

What do chemical mediators create?

A

inflammatory response: red warm swelling in the skin is hallmark of innate response

141
Q

What does inflammatory response do?

A

serve as a signal to attract other cells and chemical agents to the site

142
Q

What happens during inflammation?

A
  • increased capillary permeability and causes fever
  • produces a physical barrier that prevents the spread of pathogen
  • tissue repair is promoted
143
Q

What causes the chemical mediators’ response?

A

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
Q

What is Interleukin-1?

A

mainly made by macrophage (WBC), and helps leukocytes (WBC) fight infections

145
Q

What is the function of Interleukin-1?

A
  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
Q

What is complement proteins?

A

take parts in innate response, complement is a collective term for over 25 blood proteins (some are opsonins, some are chemotaxins)

147
Q

How are complement proteins activated?

A

by sequential proteolysis

148
Q

What is Membrane Attack Complex (Mac attack)?

A

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
Q

What are adaptive immunity also called?

A

acquired or specific immunity

150
Q

How do adaptive immunity start?

A

products of innate immune responses start the acquire responses

151
Q

What is involved in adaptive immunity?

A

lymphocytes and lymphocyte products

152
Q

What types of lymphocytes are involved in adaptive immunity?

A
  1. B cells
    - activated form = plasma cell
  2. T cells
    - Tc and Th and Tregs
153
Q

What do all lymphocytes produce?

A

cytokines

154
Q

What is specificity?

A

each individual cell recognizes a different specific pathogen

155
Q

What expands clonally?

A

T cells and B cells (able to make identical copies of itself)

156
Q

How many different B and T cells do we have?

A

millions; but we only have a few naive cells

157
Q

What are naive cells?

A

cells that have never encountered their specific antigen (no pathogen exposure)

158
Q

What are the steps for adaptive immune system cells?

A

the recognize a pathogen, expand clonally, and produce many effector cells which attack the pathogen; some cells become memory cells

159
Q

What are memory cells?

A

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
Q

What is humoral immunity?

A

B cells produce antibodies that take part in antibody-mediating immunity

161
Q

What is another term for antibodies?

A

immunoglobulins

162
Q

Where are antibodies/immunoglobulins found?

A

either a cell membrane protein of B lymphocytes or secreted by B lymphocytes

163
Q

What can membrane Ab’s be used for?

A

as markers to identify each different clone of B cells

164
Q

What happens when B cells are stimulated?

A

they mature into plasma cells

165
Q

What are plasma cells?

A

mature B cells that produce ~2000 antibody molecules per second

166
Q

How long do plasma cells live for?

A

they are short lived and die after response is over; a few memory cells survive (they remember the past infection)

167
Q

When do antibodies respond?

A

after the first and second exposure to an antigen

168
Q

When does primary Ab response happen?

A

on the first exposure to an antigen; there is a slower and delayed response and less antibody concentration

169
Q

When does secondary Ab response happen?

A

on the second exposure to an antigen; response is much faster, more antibodies produced

170
Q

Why does secondary Ab response faster?

A

because mediated by memory cells; this is the principle of why vaccination works

171
Q

How does vaccination work?

A

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
Q

What are the 5 classes of immunoglobulins (Ig)? (MADGE)

A
  1. IgM
  2. IgA
  3. IgD
  4. IgG
  5. IgE
173
Q

What is IgM?

A

immunoglobulin produced during primary responses which activates complement

174
Q

What is IgA?

A

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
Q

What is IgD?

A

found on surface of B cells with IgM (function is unknown)

176
Q

What is IgG?

A

make up 75% of plasma antibodies in adults, secondary response antibody (activates complement, opsonizes)

177
Q

What is IgE?

A

associated with allergic responses and are recognized by mast cells

178
Q

What is the structure of an antibody?

A
  • 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
Q

What are the funcions of antigens?

A
  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
Q

How much do antibodies make up of proteins found in plasma?

A

20%

181
Q

What are antibodies most effect against?

A

they are most effective against extracellular pathogens before they invade a cell
- also effective against macrobolecules

182
Q

Does antibodies damage the pathogens?

A

no, they make pathogens more visible to immune defenses or activate defenses

183
Q

How do antibodies bind?

A
  • 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
Q

What do T-cells do in adaptive immunity?

A

they mediate cellular immunity

185
Q

What do T cells need to be in?

A

direct contact with the target cell expressing an antigen

186
Q

What is a T cell receptor?

A

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
Q

Can T cell receptors bind to free antigen?

A

no, must bind to antigen displayed on Class I or II MHC

188
Q

What are the two types of MHC proteins?

A
  1. Class I MHC
  2. Class II MHC
189
Q

What is Class I MHC?

A

present on the surface of every nucleated (every cell with a nucleus) cell in the body

190
Q

What does the Class I MHC do?

A

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
Q

What does Class I MHC proteins release?

A
  • perforin: forms pores in target cell
  • granzymes: enters through the pores and triggers apoptosis
192
Q

What is Class II MHC?

A

present on the surface of specialized immune system cells (antigen presenting cells APCs)

193
Q

What do Class II MHC proteins do?

A

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
Q

What are the 4 types of immune responses?

A
  1. Extracellular bacteria
  2. Intracellular viruses
  3. Allergic responses
  4. Foreign tissue
195
Q

Which response starts first, innate or adaptive?

A

innate response starts first then adaptive response

196
Q

What is the result of a bacterial invasion?

A

results in an inflammatory response, includes redness, welling, tenderness

197
Q

What are the stages of a bacterial invasion response?

A
  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
Q

What are the stages of a bacterial invasion response?

A
  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
Q

What works together to destroy the virus and virus-infected cells?

A

T-cell mediated and humoral immunity

200
Q

What do viruses have to go through before they infect a host?

A

they have to first go through an extracellular phase; phagocytes and Ab’s help to opsonize and neutralize here

201
Q

What are the stages of response to viral infection?

A
  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
Q

What are allergies?

A

an inflammatory immune response to. anon-pathogenic antigen

203
Q

What are the inflammatory responses in allergies triggered by?

A

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
Q

What individuals develop inflammatory responses to allergens?

A

sensitive (atopic) individuals, and the resulting response is worse and causes more damage than the antigen; the range vaires from vild to fatal

205
Q

What are allergic responses?

A

hypersensitivities

206
Q

What are the two types of hypersensitivities?

A
  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
Q

What are the steps of response in an immediate hypersensitivity response (happens in minutes, Ab mediated)?

A
  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
Q

What is the two types of severity of allergic responses?

A
  1. Localized (rashes or hay fever)
  2. Systemic (anaphylactic shock)
209
Q

What happens during a systemic allergic response?

A
  • widespread vasodilation, circulatory collapse
  • bronchoconstriction
210
Q

How can you transplant foreign tissues not be ejected by the recipient’s immune system?

A
  • 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
Q

What are the two possible outcomes of the transplant?

A

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
Q

What is a common example of tissue donation?

A

blood transfusion; they don’t contain MHC proteins found on nucleated cells

213
Q

The blood groups have four blood types:

A

Type O, A, B, and AB

214
Q

What happens when the wrong blood type is introduced into the recipient?

A

the antibodies react and the cells clump (agglutinate)

215
Q

What does antibody binding activate?

A

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
Q

When do people express antibodies to RBCs?

A

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

BIOL273 (2 decks)

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