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Immunology- Unit 1 > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

Microbes result in what type of diseases?

A

Infectious diseases

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2
Q

How do extracellular microbes survive in animals?

A

By growing extracellularly and being immersed in nutrients

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3
Q

Where in the body do extracellular microbes grow?

A

In any part of the body

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4
Q

How do intracellular microbes survive and where does this occur?

A

They invade, live, and replicate intracellularly

Occurs within animal cells

Uses host- cell energy resources

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5
Q

What is an example of an intracellular microbe and broadly how does it work?

A

Viruses

Hide and multiply in host cell

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6
Q

What is one way to get rid of intracellular microbes?

A

Using antibiotics

These microbes tend to develop resistance which makes them hard to treat

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7
Q

There is a constant battle between invading microbes and _____ _____.

A

Immune system

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8
Q

Microbes are _____ in nature.

A

Waterborne.

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9
Q

Define Immunity

A

A set of cooperative defense mechanisms which provide protection from various infectious diseases

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10
Q

Define Immunopathology

A

Non-specific immune response against microbes that causes tissue injury

Also known as collateral damage

Can be the result of non-specific immune response

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11
Q

What is the response in the tissues after collateral damage occurs?

A

Tissue remodeling

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12
Q

Define Antigens

A

Non-infectious foreign substances that can elicit an immune response

Anything that is presented to the body that interacts with antibodies

Substances that induce an immune response

Anything that is presented to the body that at least generates antibodies

NOT involved with pathogen or bacteria

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13
Q

Self- antigens in the body can elicit what kind of response?

A

Autoimmune response

Critical for cells to be able to differentiate between self and non-self

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14
Q

T/F: Each microbe has many microbial antigens

A

True

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15
Q

Define Antibody

A

Protein produced by immune system when it detects antigens

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16
Q

Antigen- Antibody binding can be compared to what?

A

Lock and key

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17
Q

Define Epitope

A

Antigenic determinant

Portion of antigen molecule to which an antibody binds

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18
Q

The smallest epitope possible onto which an antibody can bind is how many amino acids? Sugar residues?

A

3 - 6 amino acids
5 - 6 sugar residues

  • can occur on unfolded (denatured) portion or folded protein
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19
Q

T/F: Antigen can NOT contain several different epitopes to which individual responses are made

A

False

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20
Q

Antibodies bind to _____ antigenic epitopes which is dependent on what property of the molecule?

A

Conformational

Dependent on folding of the molecule

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21
Q

What kind of amino acid sequences do T cell receptors recognize?

A

Linear amino acid sequences

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22
Q

Haptens are _____ that _____.

A

Very small antigens

Can bind to antibodies but cannot initiate an immune response
- do not have enough structural information to generate an immune response

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23
Q

Define Immunogens

A

Antigens that can stimulate an immune response

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24
Q

Relate Immunogens to Antigens

A

All immunogens are antigens but not all antigens are immunogens

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25
Q

How do antigens travel via fixed elements?

A

Plasma delivers antigens to tissues

Leaks into lymph nodes via capillaries and goes into secondary lymphoid organs

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26
Q

Characteristics of Mucosal Immune Tissue

A

Secondary lymphoid organ

Largest immune organ in body

Located at places with thin epithelial layers and at interface of environment and body

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27
Q

Characteristics of Innate Immunity

A

First line of defense against infection

Pre-existing

Works rapidly - response will be same every time for common/ similar things

Gives rise to acute inflammation

Has some specificity for antigens

Has no memory

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28
Q

In order for the innate immune system to have specificity for antigens, what feature must the antigen have?

A

Must be a common antigen

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29
Q

Why doesn’t the innate immune system have memory?

A

Due to lack of antigen specificity and recognition

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30
Q

Antimicrobial peptides target _____

A

Pathogenic microorganisms

Works due to osmotic lysis

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31
Q

Define Complement. How is it related to the surface of the pathogen?

A

System of plasma proteins that enhances the ability of antibodies and phagocytic cells to clear pathogens from an organism

Activated and creates membrane attack completes on surface of pathogen

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32
Q

What occurs in Acute Phase Proteins in response to tissue injury, acute infections, burns, or inflammation?

A

Change in their plasma concentrations

[] increases when have one of those responses

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33
Q

Define Cytokines

A

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

Originate from innate immune cells

Work with macrophages

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34
Q

How do cytokines work?

A

Via messaging that produces small proteins

Cells have receptors that messages bind to

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35
Q

Define Chemokines

A

Subfamily of cytokines secreted by immune cells to induce chemotaxis in nearby cells

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36
Q

What is different in Adaptive immunity compared to innate immunity?

A

Takes longer to develop

Is highly specific

Shows memory

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37
Q

T/F: generation of specific receptors is a feature of adaptive immunity

A

True

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38
Q

What is adaptive immunity controlled by?

A

Signals generated by immune cells involved in innate immune response

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39
Q

What are the two functions of cytokines?

A

Regulate growth and differentiation of all immune cells

Activate the effector functions of lymphocytes and phagocytes

Cytokines have high affinity responses

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40
Q

Cytokines act via specific _____ _____ expressed on _____ _____.

A

Signaling receptor ; target cells

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41
Q

What is the major response in the GI system related to adaptive immunity?

A

Cellular and chemical barriers

  • lymphocytes in epithelia
  • antibodies secreted at epithelial surfaces
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42
Q

Characteristics of early Innate Immune responses

A

Exists before infection

Poised to respond rapidly to infection
- provides 1st assessment of pathogen

Depends on if pathogen is extracellular or intracellular **

Responds in same way to repeated exposures to antigen

Recognizes common antigens belonging to groups of related microbes

Does NOT distinguish fine differences between microbes

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43
Q

Primary function of Phagocytes

A

Ingest and destroy microbes and get rid of damages tissues

“clean up” cell

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44
Q

What are the steps in the functional responses of phagocytes?

A
  1. Recruitment of the cells to the sites of infection
  2. Recognition of and activation by microbes
  3. Ingestion of the microbes by the process of phagocytosis
  4. Destruction of ingested microbes
    • occurs via fusion with lysosomes
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45
Q

Which cell is one of the mediators of the earliest phases of the inflammatory reactions?

A

Neutrophils

React before any other cells come into tissue

Stored in bone marrow
- Released quickly after signaled by cytokine (granulocyte colony- stimulating factor) and activates phagocytosis

Not produced de nuovo

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46
Q

What is a common feature between Mast cells, Basophils, and Eosinophils?

A

Cytoplasmic granules

- filled with various inflammatory and antimicrobial mediators

47
Q

Where are mast cells found?

A

Sites in body that are exposed to external environment

Found in close proximity to blood vessels at these locations

48
Q

What advantage do Mast cells have by being located near capillaries?

A

Allows them to regulate vascular permeability and effector- cell recruitment

49
Q

Which cell functions as the breeching between innate and adaptive system?

A

Dendritic cells

50
Q

Describe the path from monocyte to macrophage

A

Mature monocytes enter into blood circulation > Migrate into tissues where they further mature into macrophages

Occurs especially during inflammation

51
Q

Are tissue resident macrophages specific in any way?

A

Yes: have tissue specific and niche specific functions

52
Q

Where are antigens made and where are they found?

A

Antigens are made in primary lymphoid organs and are found in secondary lymphoid organs

53
Q

Describe the mechanism of chemokines

A
  1. Chemokines are sensed by cells

2. Cells move into tissues by following gradient created by chemokines

54
Q

What do chemokines regulate?

A

Cell migration and movement

55
Q

How will the immune system fight a GI infection with enteric bacteria?

A

Self cannot send immune cells bec there is no oxygen here

Immunogens produce a specific class of antibodies which are secreted at the infection site and are absorbed on the surface of the bacteria and cannot enter the enteric epithelium

56
Q

Where are most of the innate immune cells located and when are they released?

A

Most are stationed in the blood and are delivered to tissues on demand as a part of the inflammatory response/ inflammation

57
Q

T/F: Most interactions with pathogens are resolved at the local level and don’t ever encounter adaptive immunity.

A

True

58
Q

Activated phagocytes secrete _____ to promote or regulate immune responses?

A

Cytokines

59
Q

Examples of phagocytes

A

Neutrophils

Macrophages

60
Q

Describe the pathway of Neutrophils from storage to action

A

Stored in bone marrow > released quickly after signal from cytokine > phagocytosis > quickly move into tissue

61
Q

After entering the tissues, how long do neutrophils function for and how do they act?

A

Only function for 1 - 2 days before dying

Throw DNA out of cell > take in stuff/ phagocytosis > digest > die

62
Q

Functions of Tissue- Resident Macrophages

A
  1. Dedicated homeostatic functions
    • clearance of cellular debris and iron processing
  2. Tissue immune surveillance
  3. Response to infection
  4. Resolution of inflammation

Function depends on the tissue into which they are allocated

63
Q

What kind of cells are Dendritic cells and how do they act?

A

Antigen Presenting cells (APCs)

Have long surface membrane extensions (dendrites) - take antigens from site of infection and bring it to lymph nodes

64
Q

How are dendritic cells related to adaptive immunity?

A

Are potent stimulators of T cells which can induce the adaptive immunity

65
Q

How do mast cells, basophils, and eosinophils (generally) work?

A

Are designed to work against multicellular pathogens

Protect against helminths and reactions that cause allergic diseases

Tissue remodeling creates collagen pockets that are contained in the tissues

66
Q

What is the immediate response to mast cell activation?

A

Immediately release granules filled with histamine > results in dilation

67
Q

How do mast cells modulate the behavior of cells?

A

Release mediators (cytokines)

Do not have direct cell-to-cell contacts

68
Q

The innate immune system is considered what stage of the immune response and what occurs during this stage?

A

Decision- making stage

Evaluates the invader in the context of intracellular vs extracellular microbes.
- based on this, it provides instructions to adaptive immunity

69
Q

Why is phagocytosis mediated by neutrophils?

A

Neutrophils increase by 300% after infection whereas monocytes increase relative to blood cells in circulation

70
Q

How does the immune system compensate for not being able to have a ton of B and T cells circulating?

A

Generated specific receptors

B and T cells (as a group) recognize the same epitopes but 2 different individual B cells/ T cells have different receptors and different epitopes

71
Q

Describe receptors in adaptive immunity (general)

A

Receptors are specifically tailored to antigens on surface of pathogen

Recognize very minute changes

Provide extremely specific type of recognition
- based on specific receptor on surface

72
Q

Compare specificity between innate and adaptive immunity

A

I: specific for antigens shared by groups of related microbes and molecules produced by damaged host cells.
- targets common antigens

A: for microbial and nonmicroblal agents

73
Q

Compare diversity between innate and adaptive immunity

A

I: limited

A: very large diversity

74
Q

Compare memory between innate and adaptive immunity

A

I: none

A: yes

75
Q

Compare reactivity to self between innate and adaptive immunity

A

I: none

A: none

76
Q

Describe receptors in adaptive immunity

A

Receptors are specifically tailored to antigens on surface of pathogen

Extremely specific type of recognition based on specific receptor on surface

Recognize very minute changes

77
Q

What can T cells recognize?

A

Proteins only

Recognizes proteins and proteins processed and presented to them by another cell (APC) as small peptides of surface

78
Q

What can B cells recognize?

A

Can recognize anything

79
Q

What types of interactions are critical for development of specific immunity?

A

Interactions between T cells and B cells

Interactions between T cells and antigen presenting cells

80
Q

What is the 2- step recognition for adaptive immunity?

A
  1. Intracellular vs extracellular microbes
    • I = T cells
    • E = B cells
  2. Cell mediated vs humoral
    • CM = T cells = I
    • H = B cells = E
81
Q

Define Humoral Adaptive Immunity

A

Immunity that involves the production of soluble molecules (immunoglobulins)

Involves extracellular microbes

The principal defense mechanism against extracellular microbes and their toxins
- secreted antibodies can bind to these microbes and toxins and assist in their elimination

82
Q

Describe Humoral Adaptive Immunity development and mediation

A

Based on the development and maturation of B cells in the bone marrow

Mediated by antibodies in the blood and mucosal secretions by B cells

83
Q

Describe the mechanism of antibodies in Humoral Adaptive Immunity

A
  1. Antibodies recognize microbial antigens and bind with high affinity
  2. After binding, they neutralize the infectivity of the microbes
    - interacts with catalytic center and prevents activity of the enzyme
  3. Target microbes for elimination by various effector mechanisms
    • phagocytes: have high affinity receptors on surface which recognize part of antibody that is not interacting with antigen
84
Q

What is the general course of action during Humoral Adaptive Immunity?

A

B cells secrete antibodies that prevent infections and eliminate extracellular microbes

85
Q

Who is Paul Ehrlich and what discovery did he make?

A

Father of Humoral Immunity

Found that immune cells can secrete specific receptors which recognize microbial toxins and combat invading microbes
- model for the function of B cells in humoral immunity

86
Q

How is cell- mediated Immunity controlled?

A

Controlled by responses of T cells

- function in concert with antigen- presenting cells and phagocytes to eliminate microbes

87
Q

What does cell- mediated immunity mediate?

A

Mediates host defense against intracellular microbes (viruses and bacteria) where they are inaccessible to circulating antibodies

88
Q

Cell- mediated immunity is based on what and how is a response generated?

A

Based on development and maturation of T cells in thymus

Response is generated when mature T cell is stimulated by an antigen

89
Q

What is the function of cell- mediated immunity?

A

Killing infected host cells to eliminate reservoirs of infection

Have very fine tuned mechanism so only touch damaged cells
- allows it to distinguish between infected and non-infected cells

90
Q

What is the general course of action during cell- mediated immunity?

A

T helper cells activate tissue-specific macrophages to kill phagocytize microbes, or cytotoxic T cells to directly destroy infected cells

CTL takes antigens and puts them on surface in order to be tagged and killed by T cells

91
Q

Who is Elie Metchnikoff and what did he discover?

A

Father of cell- mediated immunity

Discovered special immune cells and called them phagocytes

Unable to prove that specific immunity to microbes could be mediated by cells

92
Q

Describe the phases of the adaptive immune responses

A

Antigen recognition
- B cells can interact with any antigen without any assistance

Lymphocyte activation

  • sick for 5-7 days as we develop a response
  • clonal expansion and differentiation
  • here we have reached optimal levels

Antigen elimination

Contraction (homeostasis)

  • reduction in number of cells
  • everything that is activated here will produce memory cells

Memory
- surviving memory cells engage with anti-apoptotic properties

93
Q

Describe specificity of adaptive immunity

A

Ensures that immune response to a microbe is selective to that microbe

94
Q

Describe diversity of adaptive immunity

A

Enables the immune system to respond to a large variety of antigens

95
Q

Describe memory of adaptive immunity

A

Increases the ability to combat repeat infections by the same microbe

Protects us in the long term from repeated exposures

Incredible resistance to apoptosis

96
Q

Describe clonal expansion of adaptive immunity

A

Increases the number of antigen- specific lymphocytes to keep pace with microbes

97
Q

Describe specialization of adaptive immunity

A

Generates responses that are optimal for defense against different types of microbes (not self)

98
Q

Describe contraction and homeostasis of adaptive immunity

A

Allows the immune system to recover from 1 response so that it can effectively respond to newly encountered antigens

Contraction of immune response = decreasing number of cells

99
Q

Describe non-reactivity to self of adaptive immunity

A

Prevents injury to the host during responses to foreign antigens

100
Q

What question does the clonal selection hypothesis ask?

A

How does the immune system respond to a large number of different antigens?

101
Q

Describe the clonal selection hypothesis

A

Antigen- specific clones of lymphocytes develop before and independent of exposure to antigens

  • Clones have identical receptors on their surfaces
  • clone is generated without ever seeing antigen**
102
Q

What is the benefit of immune system generating a very large number of clones during the maturation of lymphocytes?

A

It maximizes the potential for recognizing diverse microbes

103
Q

Describe the pathway of the clonal selection hypothesis

A
  1. Antigen introduced into individual
  2. Lymphocytes with receptors for this antigen seek out and bind antigens
  3. Lymphocytes are triggered to proliferate and differentiate giving rise to clones of cells specific for the antigen
  4. Cells from the clones react with the antigen to neutralize or eliminate the antigen
  5. Some antigen- specific cells late in the immune response are responsible for the memory involved in adaptive immunity
104
Q

Lymphocyte clones mature in ___ ___ ___ in the ___ of antigens. ___ of ___ ___ specific for diverse antigens enter lymphoid tissues. ___ ___ ___ are activated by antigens which act to ___ antigen. What type of responses occur?

A

Generative lymphoid organs; Absence
Clones; mature lymphocytes
Antigen- specific clones; neutralize

Antigen- specific immune responses occur

105
Q

Compare memory cells and naive cells in terms of effectiveness, number, speed of response

A

Memory cells are more effective in combating microbes

Memory cells are more numerous than naive cells specific for the antigen

Memory cells respond faster and more effectively

106
Q

What is an important goal of vaccinations?

A

Generation of memory responses

107
Q

What happens to antibody levels and memory cell numbers after each immunization?

A

Antibody levels decline with time after each immunization
= contraction of immune response

Number of memory cells increases

108
Q

Define active immunity

A

Conferred by a host response to a microbe or microbial antigen

Response is specific and has memory

Provides resistance to infection and is specific for microbial antigens

109
Q

Define passive immunity

A

Conferred by adoptive transfer of antibodies or T cells specific for the microbe
- acts via neutralization

Response is specific but does not have memory

Provides resistance to infection and is specific for microbial antigens

110
Q

Describe B lymphocytes

A

Recognize soluble antigens

Develop into antibody secreting cells

Protect against extracellular microbes

Functions: neutralization of microbe, phagocytosis, and complement activation

111
Q

Describe T helper lymphocytes

A

Recognize antigens on surfaces of antigen- presenting cells

Secrete cytokines which stimulate different mechanisms of immunity and inflammation

Help produce cytotoxic T cells

Activate macrophages

Proliferation and differentiation of T and B lymphocytes

Part of inflammatory response

112
Q

Describe cytotoxic T lymphocytes

A

Recognize antigens on infected cells and kill them

Triggers apoptosis

113
Q

Describe regulatory T cells

A

Suppress and prevent immune responses

Help to prevent unwanted reactions

Suppress other lymphocytes

Immunology- Unit 1 (3 decks)

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