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MB prep: Biochemistry. > Immunology > Flashcards

Immunology Flashcards

1
Q

Immunity may be _ or _

A

Natural or acquired

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2
Q

What is immunity

A

Immunity refers to all the properties of the host that confer resistance to a specific infectious agent. That is to say that immunity is non susceptible to the invasive pathogenic effects of foreign microorganisms or to the toxic effects of antigenic substances

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3
Q

What are the physiological mechanisms of an immune response

A
  • To distinguish foreign material from self
  • To neutralize, eliminate and metabolize that which is foreign by the physiological mechanisms of immune response
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4
Q

Acquired immunity may be _ or _

A

Passive or active

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5
Q

Another name for natural immunity

A

Innate immunity

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6
Q

What is the 1st line of defense

A

Skin, mucosal membrane, normal microbiota : Physical barrier, lymphoid cells, Antimicrobial molecules

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7
Q

How many lines of defense are there

A

3

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8
Q

What is the 2nd line of defense

A

Innate immune system: macrophages (phagocytic WBC), Natural Killer cells, Neutrophils, Complement, , Cytokines (inflammation,fever)

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9
Q

What is the 3rd line of defense

A

Adaptive immune system: Tcells, Bcells, Antibodies, Cytokins

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10
Q

Comment on the epidermis of the skin as a first line of defense

A

It forms a physical barrier to the entrance of microbes

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11
Q

Comment on mucous membrane as a first line of defense

A

Inhibits the entrance of many microbes, but not as effective as intact skin

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12
Q

Comment on the function of mucus as a first line of defense

A

Traps microbes in respiratory tract and GIT

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13
Q

Comment of lacrimal apparatus as a first line of defense

A

Tears produced from the gland, dilute and wash away irritating substances and microbes

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14
Q

Comment on saliva as a first line of defense

A

Washes microbes from surfaces of teeth and mucous membranes of mouth

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15
Q

Comment on hairs as a first line of defense

A

Filler out microbes and dust in nose

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16
Q

Comment on cilia as a first line of defense

A

Together with mucus, trap and move mic-bes and lust from upper respiratory tract.

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17
Q

Comment on epiglottitis as a first line of defense

A

Prevents microbes from entering lower respiratory tract

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18
Q

Comment on urine as a first line of defense

A

Washes microbes from urethra,

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19
Q

Comment on vaginal secretions as a first line of defense

A

Move microbes out of female reproductive tract

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20
Q

Comment on defecation and vomiting as a first line of defense

A

Expel microbes from body

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21
Q

What is innate immunity

A

Also called natural immunity, it is the type of immunity which is not acquired through previous contact with the infectious agent (or with a related species). Innate immunity response is non-specific and rapid, can affect a wide range of pathogen types and also triggers the development of acquired immunity.

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22
Q

What are some characteristics of innate immunity

A
  • It is non specific and rapid
  • It can affect a wide range of pathogen types
  • It triggers the development of subsequent adaptive immunity
  • Each pathogen is treated the same way
  • There is no immunological memory of the pathogen encounter
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23
Q

What is inflammation

A

This is an immunological response characterized by an increased migration of immune cells to a site of infection. Innate immune cells detect pathogens that bypass the physical barrier, by detecting markers on them, which triggers the secretion of signaling molecules that attract other immune cells to help convert the infection.

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24
Q

differences between innate immunity and adaptive immunity

A
  1. Innate immunity is present at birth and fights infection even without prior exposure to the pathogen, WHILE. Adaptive immunity may take a few days/weeks to become effective.
  2. Innate immunity provides a non-specific response that acts
    against a broad range of different pathogens. WHILE. Adaptive immunity provides a highly specific response, meaning it has the ability to recognize specific foreign antigen
  3. Innate immunity Recognizes pathogens but no immunological memory. WHILE. Adaptive immunity recognizes and destroys pathogens, and also retains the memory of that encounter (immunological memory)
  4. Innate immunity Activates further immune responses, specifically, adaptive immunity. WHILE. Adaptive immunity such as T-cells and B-cells, can only recognize presented antigens by Antigen Presenting Cells (APCs), a type of innate immune cell
  5. Innate immunity is complex and comprises biochemical and cellular pathways whose function is to recognize and remove invading pathogens. WHILE. Adaptive immunity focuses mainly on the production and actions of the T-cells nd the B-cells
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25
Q

dendritic cells, macrophages, mast cells and neutrophils are common in what way

A

they are all phagocytes

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26
Q

what is a phagocyte

A

A phagocyte is a type of innate immune cell that ingests and degrades pathogens.

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27
Q

In order to ingest and degrade pathogens, phagocytes …

A

phagocytes express receptors that detect pathogen-associated molecular patterns (PAMPs).

PAMPs are molecular structures that are not present in vertebrates (e.g. mammals and birds) but are found on microorganisms.

The presence of PAMPs allows innate immune cells to recognize pathogens as ‘non-self’

Toll-like receptors allow cells of the innate immune system to detect Toll-like receptors (TLRs) are a family of pattern-recognition receptors that detect pathogens via PAMPs.

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28
Q

what is the significance of the presence of PAMP

A

it allows immune cells to differentiate self from non-self (pathogens)

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29
Q

What does PAMP ancronyme

A

Pathogen-Associated Molecular Patterns

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30
Q

are PAMPs present in vertebrates

A

No, just on microorganisms

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31
Q

What does APC ancronyme

A

antigen presenting cells

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32
Q

what does TLR ancronyme

A

Toll-Like Receptors

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33
Q

what are the TLRs

A

They are a family of pattern-recognition receptors that detect pathogens via PAMPs.

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34
Q

What is TNF-a (alpha)

A

Tissue Necrosis Factor- alpha

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35
Q

describe the neutrophils

A

They are Granular leukocytes. They are the most abundant leukocytes in blood (4-10 x 109/L), upon infection production (in bone marrow) increases rapidly (up to 20 x 109/L) and stimulated by CSF secreted by many cell types

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36
Q

describe the basophils

A

release histamine, other mediators of inflammation, vesicles bind basic dyes

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37
Q

describe the eosinophils

A

phagocytic, attack parasites with toxic proteins, role in alergic reactions (astma) and in antitumor defens

38
Q

describe the dendritic cells

A

produce cytokines to recruit leukocytes and initiate adaptive immune response; major function is antigen displa

39
Q

what is the major function of the dendritic cells

A

antigen display

40
Q

what are the mast cells

A

They are tissue residing; filled with cytoplasmic granules containing histamine, heparin, prostaglandins and proteolytic enzymes; important for helminth infestation and allergies

41
Q

what are the macrophages

A

monocytes become actively phagocytic macrophages when stimulated via infection, injury; production of cytokines to activate leukocytes; secrete growth factors and enzymes to repair injured tissue

42
Q

what are the natural killer cells

A

recognize and destroy cells with features of tumor cells, cells with intracellular pathogen

43
Q

what proteins send signals between cells to coordinate and immune response

A

cytokines

44
Q

what are some important cytokines secreted by macrophages

A

-Tissue necrosis factor - Alpha
-Interleukin- I Beta
-Interleukin- 6

45
Q

where are cytokines secreted from

A

They are secreted from the cell that detected the PAMP (Pathogen Associated Molecular proteins). Such as:
-Macrophages
-Neutrophils
-Monocytes
-Mast cells
-Dendritic cells

46
Q

what cells detect cytokines

A

-Other immune cells such as macrophages, neutrophils and dendritic cells
-Non-immune cells such as endothelial cells

47
Q

Comment on the process of immune signaling

A

-When a Toll-Like Receptor (TLR) is activated by binding to a PAMP (Pathogen associated Molecular Protein), signaling cascade sends a message to the cell nucleus to turn on certain genes that produce cytokines, such as: Tissue necrosis factor - Alpha, Interleukin- I Beta, Interleukin- 6.

-The cytokines are produced by the cells that detects the PAMP, FOR EXAMPLE: neutrophils, monocytes, macrophages, mast cells, dendritic cells.

-The cytokines can be detected by other immune cells: Immune cells (macrophages, neutrophils, dendritic cells) and non-immune cells (endothelial cells)

-The cytokines instruct immune cells to fight the infection. They are produce in response to stimuli that signal information. e.g antibodies, antigens, PAMPs

48
Q

function of TNF-alpha

A

TNF-alpha acts on vascular walls to allow the entry of cells, complement and antibodies into the tissues to help contain the infection

49
Q

Interleukin-1 Beta function?

A

it helps the immune cells to leave the blood and enter the tissues, it also activates the cells of the adaptive immune system (lymphocytes).

50
Q

Interleukin-6 function

A

It activates lymphocytes and increases production of antibodies

51
Q

how many proteins are of the coplement system

A

> 30

52
Q

what are some major complement proteins you know

A

C5a, C3a, C3b

53
Q

what are the functions of the complement system

A

-Protection against infection
-Regulation of inflammatory processes
-Removal of damaged or altered cells
-Regulating adaptive immune responses
-Sending of danger signals throughout the body
-Activation of adaptive immunity

54
Q

what is the complement system

A

The complement is a system of interacting protein molecules that aids in the removal of pathogens from an animal and forms an important component of innate immunity.

Functions of the complement
-Protection against infection
-Regulation of inflammatory processes
-Removal of damaged or altered cells
-Regulating adaptive immune responses
-Sending of danger signals throughout the body
-Activation of adaptive immunity

It is composed of > 30 proteins, including C5a, C3a and C3b.
3 pathways trigger an activation cascade and the pathogen
surface is a key site where complement activation occurs.

55
Q

what is the site of complement activation

A

the pathogen surface

56
Q

what are the 3 pathways of complement action

A

1) Enhance phagocytosis (opsonization) — C3b attaches to the cell surface of microorganisms to flag them for destruction by phagocytes;

2) Initiate inflammation C5a and C3a attract and activate neutrophils and mast cells and enhance TIR-induced production of proinflammatory cytokines;

3) Kill microbes the membrane attack complex (MAC) creates pores in cell membranes to kill bacteria

57
Q

what is MAC

A

Membrane Attack Complex

58
Q

explain the opsonization pathway of the complement

A

1) Enhance phagocytosis (opsonization) — C3b attaches to the cell surface of microorganisms to flag them for destruction by phagocytes;

59
Q

explain the innate inflammation pathway of the complement system

A

Initiate inflammation—— C5a and C3a attract and activate neutrophils and mast cells and enhance TIR-induced production of proinflammatory cytokines;

60
Q

explain the killer microbes pathway of the complement system

A

Kill microbes—- the membrane attack complex (MAC) creates pores in cell membranes to kill bacteria

61
Q

what are the innate immunity response to infection

A

-Phagocytosis
-Inflammation

62
Q

Comment on phagocytosis

A

-When a pathogen is detected, the phagocyte extends itself around the pathogen, taking the pathogen into an internal compartment inside the phagocyte, in a process termed phagocytosis.

-Phagocytes produce a number of toxic products that kill ingested pathogens:
-Some phagocytes contain primary granules which release antimicrobial peptides and protease enzymes onto the pathogen, which have widespread activity against different pathogens.
-The pathogens are digested by these toxic products in the intracellular compartment, and the broken-down products are then released from the phagocytes.
-During phagocytosis, the phagocyte undergoes a period of increased oxygen consumption and during this time enzymes are activated to produce reactive oxygen species, which are also toxic to the ingested bacteria.
-Also, phagocytes become activated by pathogens causing them to release cytokines, which signal to other immune cells for the destruction of pathogens.

63
Q

what are the ways phagocytes destroy pathogens

A

-Some phagocytes contain primary granules which release antimicrobial peptides and protease enzymes onto the pathogen, which have widespread activity against different pathogens.
-The pathogens are digested by these toxic products in the intracellular compartment, and the broken-down products are then released from the phagocytes.
-During phagocytosis, the phagocyte undergoes a period of increased oxygen consumption and during this time enzymes are activated to produce reactive oxygen species, which are also toxic to the ingested bacteria.
-Also, phagocytes become activated by pathogens causing them to release cytokines, which signal to other immune cells for the destruction of pathogens.

64
Q

The primary granules in the phagocytes secrete

A

-antimicrobial peptides,
-protease enzymes.

65
Q

why do phagocytes go through a period of high oxygen consumption

A

It is because, during this time, enzymes are activated to produce reactive oxygen species which are also toxic to bacteria.

66
Q

comment on inflammation

A

-The detection of PAMPs on pathogens by TLRs on phagocytes initiates a signalling cascade that results in the phagocyte secreting cytokines.

-Cytokines are responsible for the process known as inflammation, which helps more immune cells reach the site of infection in order to increase the strength of the immune assault against the infecting pathogen.

-Cytokines move through the tissues and cause changes to the cells that make up the blood vessel walls, known as endothelial cells.

-Blood vessels dilate and become leaky and express adhesion molecules on their surface.

-Immune cells bind to the adhesion molecules and then squeeze through the gaps in blood vessel walls to enter the tissues.

-Once in the tissues, immune cells follow a type of cytokine, called chemokines, which lead the cells to the focus of infection.

-This influx of immune cells to the site of infection produces the characteristic signs of inflammation; redness, swelling, heat and pain.

-Neutrophils arrive at the infection site first, followed by monocytes and immature dendritic cells (DCs).

-Once there, certain chemokines and complement proteins can cause activation of these immune cells. The activated immune cells are equipped to fight the infection through phagocytosis.

67
Q

once in the tissues, immune cells follow ___ type of cytokines to the focus of the infection

A

chemokines

68
Q

what are the characteristic signs of inflammation

A

-redness
-swelling heat
-pain

69
Q

what cells reach the site of infection first (in order)

A

Neutrophils> Monocytes> Immature dendritic cells

70
Q

what initiates the inflammation process

A

detection of PAMPs on Pathogens by TLRs on phagocytes

71
Q

What is natural/ innate immunity

A

It is that type of immunity which is not acquired through previous contact with the infectious agent (or with a related species). Little is known about the mechanisms responsible for this form of resistance.

72
Q

What is species immunity under natural/ innate immunity

A

A given pathogenic microorganism is often capable of producing disease in one animal species but not in another e.g the bacillus of avian tuberculosis causes disease in birds but almost never in human.

73
Q

what is racial basis of immunity under natural/innate immunity

A

Within one animal species there may be marked racial and genetic differences in susceptibility e.g. person with sickle cell anemia are highly resistant to Plasmodium falciporum infection.

74
Q

what is individual resistance under natural/innate immunity

A

As with biologic phenomena, resistance to infection varies with different individuals of the same species and race, following a distribution curve for the host population.

75
Q

what is ‘differences due to age’ under natural/innate immunity

A

In general, the very young and the elderly are more susceptible to bacterial disease than person in other age groups. However, resistance to tuberculosis is higher at 5-15 years than before or after. Many age differences in specific infections can be related to physiologic factors

76
Q

what is passive immunity

A

Passive immunity is a state of relative temporary insusceptibility to an infectious agent that has been induced by the administration of antibodies against that agent which have been formed in another host rather than formed actively by individual himself

77
Q

why does passive immunity last for a short time

A

Passive protection lasts only a short time, usually a few weeks at most because the antibody molecules are decaying steadily while no new ones are being formed.

78
Q

what kind of infections are passive immunity least effective

A

Invasive bacterial infection

79
Q

give examples of passive immunity

A

-When an illness is largely attributed to a toxin (e.g. diphtheria, tetanus, botulism), the passive administration of antitoxin is of the greatest use because large amount of antitoxins can be made immediately available for neutralization of the toxin.

-In certain virus infections (e.g. measles, infectious hepatitis), the administration of specific antibodies (such as human pooled gamma globulin) during the incubation period may result in prevention or modification of the clinical disease

-Passive immunity resulting from the uterus transfer to the fetus of antibodies formed earlier in the mother protects the newborn child . during the first months of life against some coming infections.

-This passive immunity (acquired from the mother’s blood) may be reinforced by antibodies taken up by the child in mother’s milk (particular colostrums), but that immunity vanish at age 4-6 months.

80
Q

comment on passive immunity for toxins

A

When an illness is largely attributed to a toxin (e.g. diphtheria, tetanus, botulism), the passive administration of antitoxin is of the greatest use because large amount of antitoxins can be made immediately available for neutralization of the toxin.

81
Q

comment on passive immunity for viral infections

A

In certain virus infections (e.g. measles, infectious hepatitis), the administration of specific antibodies (such as human pooled gamma globulin) during the incubation period may result in prevention or modification of the clinical disease

82
Q

comment on passive immunity from uteral transfer

A

Passive immunity resulting from the uterus transfer to the fetus of antibodies formed earlier in the mother protects the newborn child . during the first months of life against some coming infections.

83
Q

comment on passive immunity from breast milk

A

This passive immunity (acquired from the mother’s blood) may be reinforced by antibodies taken up by the child in mother’s milk (particular colostrums), but that immunity vanish at age 4-6 months.

84
Q

immunity obtained from colostrum last for how long

A

4-6 months

85
Q

what is active immunity

A

Active immunity is a state of resistance built up in an individual following effective contact with foreign antigens e.g. microorganisms or their products.

-‘Effective contact’ may consist of clinical or subclinical infection, injection with live or killed microorganisms or their antigens, or absorption of bacterial products

86
Q

the effective contact of active immunity consists of:

A

-clinical or subclinical infection,
-injection with live or killed microorganisms or their antigens, -absorption of bacteria? products (e.g. toxins, toxoids).

87
Q

list differences between active and passive immunity

A
  1. Definition: Active immunity is the immunity that develops in response to an antigen, while passive immunity is the immunity that is acquired from another source.
  2. Source of immunity: Active immunity is acquired through exposure to an antigen, while passive immunity is acquired through the transfer of antibodies from another individual or animal.
  3. Duration of immunity: Active immunity provides long-lasting protection, while passive immunity provides temporary protection.
  4. Onset of immunity: Active immunity takes time to develop, while passive immunity provides immediate protection.
  5. Types of immunity: Active immunity can be naturally acquired through infection or artificially acquired through vaccination, while passive immunity can be naturally acquired through placental transfer or artificially acquired through injection of antibodies.
  6. Memory response: Active immunity results in the production of memory cells, which provide long-term protection against future infections, while passive immunity does not result in the production of memory cells.
  7. Specificity of immunity: Active immunity provides specific protection against a particular antigen, while passive immunity provides non-specific protection against a range of antigens.
  8. Degree of protection: Active immunity provides a higher degree of protection than passive immunity.
88
Q

what disorders exhibit antibody formation dysfunction

A
  • B.cell deficiency
  • T cell dysfunction
  • Aggamaglibulinemia
89
Q

What is humoral immunity

A

-Active production of antibodies against antigens of microorganism or their products.

-Antibody formation is disturbed in certain individual with agammaglobulinemia, B cell deficiency or T cell dysfunction.

90
Q

what is cellular immunity

A

-Although antibodies arise in response to foreign bodies, they play a role in the defense in an individual from invading cells.

-In this case circulating thymus dependent cells recognize materials and initiate a chain of responses that include:
-mononuclear inflammatory reactions
-cytotoxic destruction of invading cells (microbial graft of neoplastic)
-activation of cytotoxic macrophages
-Delayed hypersensitivity to reactions in tissues

91
Q

what cells recognize foriegn bodies and initiate a chain of responses?

A

thymus dependent cells (T cells basically)

92
Q

what include the chain of responses initiated by the thymus dependent cells

A

-mononuclear inflammatory reactions
-cytotoxic destruction of invading cells (microbial graft of neoplastic)
-activation of cytotoxic macrophages
-Delayed hypersensitivity to reactions in tissues

MB prep: Biochemistry. (15 decks)

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