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Immunology > Overview of Immune Responses > Flashcards

Overview of Immune Responses Flashcards

1
Q

Immunity

A

a set of cooperative defense mechanisms which provide protection from various diseases

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2
Q

extracellular microbes

A

able to survive in animals by growing extracellularly being simply immersed in nutrients

can live in blood, lymph and interstitial tissue

ex. e. coli

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3
Q

intracellular microbes

A

invade and live and replicate intracellularly within animal cells where they utilize host-cell energy sources

ex. salmonella and viruses

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4
Q

multicellular

A

…… worms…… helminthes

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5
Q

all microbes can

A

grow, reproduce, and infect humans

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6
Q

types of parasites

A

worms, protozoans, fungi, bacteria, viruses

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7
Q

why are fungi difficult to treat

A

because they are eukaryotes which increases likelihood that treatment will effect self

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8
Q

immune system

A

comprised of immune cells and molecules (that are dissolved in plasma, interstitial tissue, and lymph) which collectively mediate an immune response

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9
Q

immunopathology

A

tissue injury caused by an immune response against microbes (because immune response creates inflammation which causes harsh environment, killing pathogens as well as healthy tissue)

aka collateral damage

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10
Q

antigens (Ags)

A

noninfectious foreign substances that can elicit an immune response

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11
Q

autoimmune response

A

pathological condition in which self antigens (Ags) in the body can elicit an autoimmune response

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12
Q

Antigens (Ags) include:

A

proteins, carbohydrates, lipids, and nucleic acids

  • any polymers can invoke immune response
  • size is very important

in regards to protein Ags - 5 or 6 amino acids in length are big enough to generate immune response, anything smaller and there isn’t enough structural information for immune system to recognize as non-self

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13
Q

each microbe has many

A

microbial Ags which can be recognized by the immune system

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14
Q

an antibody (Ab) is

A

a protein produced by the immune system when it detects antigens

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15
Q

an epitope (antigenic determinant) is

A

a portion of an Ag molecule to which an antibody binds

antigens can have multiple epitopes

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16
Q

antibody binds to epitope through

A

Van der Waal interactions

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17
Q

antibodies bind to what kind of epitopes

A

conformation and linear epitopes

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18
Q

T-cell receptors recognize

A

linear amino acid sequences on antigens

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19
Q

immunogens

A

antigens that can stimulate an immune response

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20
Q

haptens

A

very small antigens that can bind to antibodies but don’t initiate an immune response

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21
Q

the immune system comprises 2 elements:

A

fixed and mobile elements

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22
Q

fixed elements of immune system consists of

A

the lymphoid organs

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23
Q

primary (generative) fixed elements

A

bone marrow (all immune cells except T-cells are generated here)

thymus (T-cells are generated here)

*generate centrally and then migrate and circulate in periphery

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24
Q

secondary fixed elements

A

spleen and lymph nodes

mucosal immune tissues

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25
Q

mobile elements

A

immune cells

soluble (humoral) components: antibodies, complement, acute phase proteins

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26
Q

innate immunity (natural immunity)

A

first line of defense against infection

exists even before infection and are poised to respond rapidly to infections

reacts to products of microbes and injured cells of the body

responds in same way to repeated exposures to antigen

recognizes common antigens belonging to groups of related microbes (gram-positive vs gram-negative) - does not distinguish fine differences between microbes

  • works rapidly
  • gives rise to an acute inflammation
  • has some specificity for antigens (doesn’t attack self)
  • has no memory
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27
Q

adaptive immunity

A
  • takes longer to develop
  • is highly specific
  • shows memory (remembers antigen it has encountered previously
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28
Q

most encounters with pathogens are resolved at the level of

A

innate immunity

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29
Q

components of innate immunity

A

cellular and chemical barriers: skin, mucosal epithelia, antimicrobial peptides

blood proteins: complement, acute phase proteins, cytokines, chemokines (humoral innate immunity)

cells: phagocytes (macrophages, neutrophils), dendritic cells, natural kills cells, innate lymphoid cells

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30
Q

humoral/soluble components of innate immunity

A 
antimicrobial peptides
complement
acute phase proteins (APPs)
cytokines
chemokines
phagocytes
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31
Q

antimicrobial peptides

A

small peptides which target pathogenic microorganisms ranging from viruses to parasites

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32
Q

complement

A

is a system of plasma proteins that enhances (complements) the ability of antibodies and phagocytic cells to clear pathogens from an organism

acts in cascade manner

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33
Q

acute phase proteins (APPs)

A

are a large group of blood proteins whose plasma concentrations change in response to tissue injury, acute infections, burns, or inflammation

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34
Q

cytokines

A

large group of small secreted and membrane-bound proteins with diverse structures and functions which regulate and coordinate many activities of the cells of innate and adaptive immunity

are cell signaling molecules that aid cell to cell communication in immune responses

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35
Q

chemokines

A

represent a subfamily of cytokines secreted by immune cells to induce chemotaxis (movement) in nearby cells

large subset of structurally related cytokines that regulate cell migration and movement

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36
Q

phagocytes (macrophages and neutrophils)

A

are immune cells that have the ability to ingest and digest microbes

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37
Q

components of adaptive immunity

A

cellular and chemical barriers: lymphocytes in epithelia; antibodies secreted at epithelial surfaces

blood proteins: antibodies and cytokines/chemokines (produced by B and T cells)

cells: B and T Lymphocytes

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38
Q

specificity for Innate vs Adaptive Immunity

A

Innate: can recognize common antigens on self; microbes and molecules produced by damaged host cells

Adaptive: for specific (unique) microbial and nonmicrobial antigens

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39
Q

diversity for Innate vs Adaptive Immunity

A

Innate: limited; germline encoded

Adaptive: very large; receptors are produced by somatic recombination of gene segments

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40
Q

memory for Innate vs Adaptive Immunity

A

Innate: none

Adaptive: yes

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41
Q

reactivity to self Antigens for Innate vs Adaptive Immunity

A

Innate: none

Adaptive: none

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42
Q

primary infection

A

patient has never seen the pathogen; never was vaccinated against this type of pathogen;

sick 7-10 days

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43
Q

many cells and molecules of the innate immune system are also

A

used by the adaptive immune system and vice versa

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44
Q

in addition to inflammation, the innate immune system is a

A

decision-making phase of an immune response

45
Q

the innate immune system evaluates the invader in the context of ____ and then provide the instructions to adaptive immunity

A

intracellular vs extracellular microbes

46
Q

if the immune system discovers extracellular infection (blood, interstitial tissue), what complements the innate immune system

A

HUMORAL-MEDIATED

antibodies

polymorphonuclear cells

phagocytes

47
Q

if the immune system discovers intracellular infection (pathogens are hiding), how are pathogens eliminated?

what complements innate immune system?

A

CELL-MEDIATED

need to kill cells, releasing pathogens, then track down and eliminate pathogens

cytotoxic T cells

natural killer cells

phagocytes

48
Q

functions of cytokines

A
  1. regulate growth and differentiation of all immune cells (growth factors)
  2. activate the effector functions of lymphocytes and phagocytes
49
Q

each cytokine acts via a

A

specific signaling receptor expressed on target cells

50
Q

cells of innate immunity

A

neutrophil, eosinophil, basophil, mast cells, monocyte, macrophage, dendritic cell, natural killer

51
Q

most of innate immune cells are stationed

A

in the blood and delivered into tissues on demand as a part of inflammatory response

52
Q

primary function of phagocytes (neutrophils and macrophages)

A

to ingest and destroy microbes and get rid of damaged tissues by process called phagocytosis

53
Q

steps in functional responses of phagocytes

A
  1. chemokine-mediated recruitment of the cells from the blood and surrounding tissues to the sites of infection/inflammation
  2. receptor-dependent recognition of microbes and activation of phagocytes
  3. formation of phagosome and ingestion of the microbes
  4. intracellular destruction of ingested microbes in lysosomes
54
Q

activated phagocytes also secrete cytoines/chemokines to

A

promote and/or regulate immune responses

55
Q

most abundant white blood cells in blood

A

neutrophils

56
Q

neutrophils are polymorphonuclear leukocytes because

A

their nucleus is segmented into three to five connected lobules

57
Q

neutrophils mediate the

A

earliest phases of inflammatory reactions

58
Q

properties of neutrophils

A

produced in the bone marrow and arise from a common precursor that also gives rise to monocytes

production of neutrophils is stimulated by cytokine called granulocyte colony-stimulating factor (G-CSF)

adult produces more than 1x10^11 neutrophils per day

are short-lived blood cells which circulates in the blood for hours or a few days

after entering tissues, they function only for 1-2 days and then die

59
Q

mononuclear phagocytes

A

blood monocytes and residents tissue macrophages

60
Q

cells of the mononuclear lineage arise from committed precursor cells in the bone marrow which is controlled by

A

monocyte/macrophage colony-stimulating factor (M-CSF)

61
Q

mature monocytes enter blood circulation and then

A

migrate into tissues where they further mature into macrophages, especially during inflammation

62
Q

mononuclear cells (blood monocytes and resident tissue macrophages) play a central role in both

A

innate and adaptive immunity

63
Q

many tissues are populated with long-lived resident macrophages which assume

A

specialized phenotypes depending on the organ

64
Q

resident macrophages are . a heterogeneous population of immune cells that fulfill tissue-specific functions including:

A
  1. maintenance of tissue homeostasis via phagocytic clearance of cellular debris and iron processing
  2. tissue immune surveillance
  3. control of an innate immune response to infection
  4. antigen-presentation to T cells
  5. contraction of the immune response and resolution of inflammation
65
Q

dendritic cells are of ____ immunity

A

innate

66
Q

like tissue macrophages, dendritic cells are ____

A

professional antigen-presenting cells (APCs)

67
Q

dendritic cells are potent stimulators of ____

A

T cells to induce the adaptive immunity

68
Q

most dendritic cells are differentiated in tissue from

A

blood monocytes

69
Q

other dendritic cell subpopulations are slowly self-renewing cells including:

A
  1. langerhans cells residing in the epidermis of the skin
  2. kupffer cells of the liver
  3. microglia of the CNS
70
Q

myeloid dendritic cells are derived from ____ and differentiated from peripheral blood mononuclear cells (PBMCs)

A

monocytes

71
Q

dendritic cells can be broadly divided to ____ and ____

A

myeloid dendritic cells

plasmacytoid dendritic cells

72
Q

mast cells, basophils, eosinophils play roles in what time of immunity

A

innate and adaptive immune responses

73
Q

mast cells, basophils, and eosinophils help protect against ____ and mediate reactions that cause ____

A

helminthes

allergic diseases

74
Q

mast cells, basophils, and eosinophils all contain

A

cytoplasmic granules filled with various inflammatory and antimicrobial mediators

75
Q

mast cells are common at sites in the body that are exposed to

A

the external environment, such as the skin where they can regulate vascular permeability and effector-cell recruitment

76
Q

mast cells do not have direct cell-cell contact with local cell populations, however they can still modulate the responses of other neighboring immune cells through the release of

A

mediators

77
Q

two branches of adaptive immunity

A

humoral and cell-mediated

78
Q

two major types of lymphocytes

A

B cells and T cells

79
Q

interactions between T cells and B cells, as well as T cells and antigen-presenting cells, are critical to the development of

A

specific immunity

80
Q

development and maturation of T cells occurs in

A

the thymus

81
Q

development and maturation of B cells mature mainly in the ____

A

bone marrow

82
Q

humoral immunity

A

immunity that involves production of soluble molecules- immunoglobulins

83
Q

t-cell

A

intracellular

84
Q

b-cell

A

extracellular

85
Q

humoral immunity is mediated by antibodies in the ___ and ____, which are produced by B lymphocytes (also called B cells)

A

blood and mucosal secretions

86
Q

functions of antibodies

A
  1. recognize microbial antigens
  2. neutralize the infectivity of the microbes
  3. target microbes for elimination by various effector mechanisms
87
Q

humoral adaptive immunity is the principal defense mechanism against ____ because ____

A

extracellular microbes and their toxins

secreted antibodies can bind to these microbes and toxins and assist in their elimination

88
Q

cell-mediated immunity is controlled by responses of

A

T lymphocytes (also called T cells) which often function in concert with antigen-presenting cells and phagocytes to eliminate microbes

89
Q

CMI mediates host defense against

A

intracellular microbes, such as viruses and some bacteria, where they are inaccessible to circulating antibodies

90
Q

function of CMI

A

killing infected host cells (by apoptosis) to eliminate reservoirs of infection

91
Q

some T lymphocytes (called T helper lymphocytes) also help B cells to make

A

effective antibodies thereby contributing to eradication of extracellular microbes

92
Q

in humoral immunity, B lymphocytes secrete antibodies that prevent infections and eliminate

A

extracellular microbes

93
Q

functions of T helper cells

A
  1. activate macrophages to kill phagocytized microbes
  2. become cytotoxic T lymphocytes (CTLs) to directly destroy infected host cells, leaving pathogens unprotected, allowing pathogens to be recognized as extracellular in which humoral immunity can eliminate
94
Q

father of humoral immunity

A

paul ehrlich, postulated that immune cells can secrete receptors (he called side chains) which recognize microbial toxins (we now call them antigens) and combat invading microbes

95
Q

father of cell-mediated immunity

A

elie metchnikoff, discovered phagocytes which he believed are the principal effector mechanism of immunity

he was unable to prove that specific immunity to microbes could be mediated by cells

cellular theory of immunity became firmly re-established in the 1950s when it was shown that resistance to an intracellular bacterium listeria monocytogenes could be tranferred with cells but not with serum

96
Q

properties of adaptive immunity:

  1. specificity
  2. diversity
  3. memory
  4. clonal expansion
  5. specialization
  6. contraction and homeostasis
  7. non reactivity to self
A
  1. specificity: ensures that the immune response to a microbe (or nonmicrobial antigens) is selective to that microbe or antigens
  2. diversity: enables the immune system to respond to a large variety of antigens
  3. memory: increases the ability to combat repeat infections by the same microbes
  4. clonal expansion: increases the number of antigen-specific lymphocytes to keep pace with microbes
  5. specialization: generates responses that are optimal for defense against different types of microbes
  6. contraction and homeostasis: allows the immune system to recover from one response so that it can effectively respond to newly encountered antigens
  7. non reactivity to self: prevents injury to the host during responses to foreign antigens
97
Q

clonal selection hypothesis

A

suggested by Dr. Jerne and furthered by Dr. Burnet

states that antigen-specific clones of lymphocytes develop before and independent of exposure to antigen

98
Q

a clone refers to

A

a lymphocytes of one specificity and its progeny

99
Q

immune system generates large number of clones which

A

maximize the defense potential for recognizing diverse microbes

100
Q

hypothesis of clonal selection stepss

A
  1. lymphocyte clones mature in generative (primary) lymphoid organs (bone marrow and thymus), in the absence of antigens (HEALTH)
  2. clones of mature lymphocytes specific for diverse antigens enter lymphoid tissues (DISEASE)
  3. antigen-specific clones are activated (“selected”) by antigens (CLONAL EXPANSION/DIFFERENTIATION)
  4. antigen-specific immune responses occur
101
Q

hypothesis of clonal selection

A

each antigen selects a preexisting clone of specific B cells and stimulates proliferation and activation of that clone

same principle applies to T lymphocytes

102
Q

when antigen is introduced into an individual, lymphocytes with receptors for this antigen seek out and bind antigens and are triggered to

A

proliferate and differentiate giving rise to clones of cells specific for the antigen

103
Q

cells from clones (or their products) specifically react with the antigen to

A

neutralize or eliminate antigen

104
Q

some antigen-specific cells late in the immune response is responsible for

A

the memory involved in adaptive immunity

105
Q

phases of adaptive immune responses

A
  1. antigen recognition: naive T lymphocyte requires antigen presenting cell to recognize; Naive B lymphocyte recognizes on its own
  2. lymphocyte activation : clonal expansion and differentiation
  3. antigen elimination: antibodies and effector T cells
  4. contraction (homeostasis): apoptosis
  5. memory: surviving memory cells
106
Q

expanded lymphocyte clones die in

A

contraction phase and homeostasis is restored

107
Q

a few activated lymphocytes become antigen-specific

A

memory cells which may survive for years after the infection

108
Q

memory cells are ____ numerous than naive cells specific for the antigen and respond ____ and ____ effectively than do naive cells

A

more

faster

more

109
Q

generation of memory responses is important goal of

A

vaccination

Immunology (23 decks)

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