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Immunology > Immunity to Microrganisms > Flashcards

Immunity to Microrganisms Flashcards

1
Q

What is innate immunity?

A

numerous non-specific barriers to infection that limit entry of or aid in rapid clearance of microorganisms

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2
Q

What are some of the major types of innate immunity?

A

skin, pH barriers (stomach, vagina), flushing, lysozymes, phagocytes, complement

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3
Q

Describe skin as a barrier

A

barrier to infection and produces fatty acids toxic to some bacteria

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4
Q

Describe pH barriers

A

organs such as the stomach or the vagina are acidic leading to the destruction of bacteria

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5
Q

Describe flushing

A

Many epithelial surfaces are cleaned by ciliary action or flushing such as the urinary tract

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6
Q

What is lysozyme?

A

present in tears, nasal secretions, and saliva; destroys cell walls

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7
Q

What are phagocytes?

A

macrophages and neutrophils that act to phagocytize invading pathogens without specific immune recognition.

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8
Q

What is complement?

A

can be fixed on the surface of many bacteria and yeast due to alternative pathway activation; leading to opsination or direct lysis

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9
Q

Where are most bacteria killed?

A

inside phagocyte

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10
Q

How do neutrophils and phagosomes know what to engulf?

A

they have receptors for many bacterial constituents

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11
Q

What is the fate of most bacteria that enter the body?

A

Most are killed and cannot cause disease

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12
Q

For the bacteria that do cause disease, how dos this occur?

A

Bacteria have evolved to defeat innate host defenses

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13
Q

What enables bacteria to evade hosts?

A

Virulence factors

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14
Q

Give examples of some virulence factors

A

Surviving acidic environment of the stomach (salmonella typhosa), spreading factors, toxins that inhibit or kill immune cells, antiphagocytic capsules, proteins that block opsination, antiphagocytic factors, attachment to epithelium

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15
Q

What is protein A

A

Protein produced by staph aureus that binds to and blocks opsinizing activity of IgG

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16
Q

What is S. pneumonia’s prime virulence factor?

A

antiphagocytic capsule

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17
Q

What bacteria can survive the acid environment of the stomach?

A

Salmonella typhosa

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18
Q

How can bacteria survive the phagosome?

A

Survive the digestive enzymes of the phagolysosome or prevent the fusion of the lysosomes with the phagosomes

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19
Q

What is the primary adaptive immune response to bacteria?

A

antibody

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20
Q

How does antibody fight bacteria?

A

prevent attachement to epithelium (IgA)
trigger complement leading to increased opsinization or lysis
binding to antiphagocytic M proteins or capsules, preventing the antiphagocytic activity and acting as an opsonin
kill bacteria faster thru opsinization
neutralize toxins
neutralize spreading factors like tissue damaging enzymes

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21
Q

What happens to bacteria that survive in normal macrophages in the presence of activated macrophages?

A

killed by activated macrophages

22
Q

What type of bacteria can survive in the phagosome?

A

facultative intracellular parasites

23
Q

Can antibody help clear facultative intracellular organisms that live in the phagosome?

A

No, they can only help them enter the phagosome.

24
Q

How are macrophages activated to kill microorganisms?

A

T-helper 1 response

25
Q

When activating a macrophage doesn’t work what happens?

A

Cytotoxic T cell CD8 needed to kill the infected macrophage, releasing the bacteria to be eaten by immunocompetent macrophage

26
Q

Which infections are most likely cleared by cell mediated immunity?

A

Listeria monocytogenes, mycobacterium tuberculosis, M. leprae

27
Q

What is cell mediated immunity?

A

immunity transferred between cells, not serum

28
Q

What cytokines are secreted by TH1 cells? What do TH1 cells do?

A

IL-2 and IFN-gamma; activate macrophages and B cells, opsonize antibodies such as IgG1

29
Q

What do TH2 cells secrete? What do they do?

A

IL-4 and IL-5; general activation of B cells to make antibody

30
Q

IFN-gamma and CD40 ligand

A

TH1; activates macrophages to destroy engulfed bacteria

31
Q

Fas ligand/ LT

A

TH1; kills chronically infected macrophages and releases bacteria to be destroyed by healthy macrophages

32
Q

IL-2

A

TH1; induces T cell proliferation to increase the number of effector T cells

33
Q

IL-3 and GMF-CSF

A

TH1;induces macrophage differentiation in the bone marrow

34
Q

TNF-alpha and LT

A

TH1; activates endothelium to induce macrophage adhesion and exit from blood vessel at site of infection

35
Q

CXCL2

A

TH1; causes macrophages to accumulate at site of infection

36
Q

Specific immunity is a function of

A

T cells

37
Q

Non-specific killing is a function of

A

activated macrophages

38
Q

What response is most important for clearing parasites?

A

T cell response

39
Q

What is the role of cytotoxic T cells in parasitic infections?

A

rarely kill the parasite, but kill parasite infected cells

40
Q

What is the most important mechanism of parasite clearance? Why?

A

Macrophage activation; parasites can survive in macrophages that aren’t activated, but are quickly killed upon their activation

41
Q

What role does T cell dependent granulomata formation play?

A

Interaction with activated macrophages that accumulate and release fibroblast growth factors; walls off the pathogen from the host

42
Q

How are eosinophils activated? what is their role?

A

T cells produce cytokines that cause infiltration and increased produciton of them; kill parasitic worms

43
Q

what do eosinophils secrete to kill parasitic worms?

A

major basic protein

44
Q

What type of reaction does IgM and IgG use to kill blood borne parasites?

A

complement mediated reaction

45
Q

How can antibody neutralize some parasites?

A

block uptake in receptor

46
Q

How can antibody act as an opsonin

A

enhances Fc and C3b mediated phagocytosis

47
Q

What is the role of IgE

A

Very important to immune response to helminths; mast cells can kill them; may be opsonin for macrophages and eosinophils

48
Q

What is antibody dependent cellular cytotoxicity? What cells are invovled?

A

Potent mechanism for destruction of some organisms; macrophages, neutrophils, eosinophils, and mast cells

49
Q

What are the 4 ways parasites escape the immune response?

A

Inaccessibility, Avoidance of recognition, immunosuppression, surviving in macrophages

50
Q

How do parasites become inaccessible?

A

Hide in host cells, exist in gut, form cysts

51
Q

How can parasites avoid recognition

A

vary antigen express or pick up host antigen to appear like self

Immunology (7 decks)

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