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1
Q

APCs perform which of the following functions in adaptive immune responses

A

display MHC-associated peptides on their cell surfaces for surveillance by t lymphocytes

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2
Q

which one of the following statements about dendritic cells is true

A

immature dendritic cells are ubiquitously present in skin and mucosal tissues

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3
Q

which of the following statements about t cell tolerance to self proteins is accurate

A

self peptide/self MHC complexes are formed and displayed by antigen-presenting cells in both class I and class II MHC pathways, but T cells that recognize these complexes usually are not present or are functionally inactive

(t cells inactive when self proteins present)

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4
Q

D 2023
which of the following is the main criterion that determines whether a protein is processed and presented via the class II MHC pathway in an APC?

A

only present with vesicular compartment of the APC during processing

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5
Q

D 2023
young adult is exposed to a virus that infects and replicates in mucosal epithelial cells of the upper respiratory tract. Cytotoxic T lymphocytes CTL are mobilized to combat this infection because

A

mucosal epithal cells express clsas I MHC molecules and are able to process cytoplasmic viral proteins and display complexes of class I MHC and bound viral peptides on their cell surfaces

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6
Q

T cell receptor TCR complex differs from an immunoglobulin molecule in which of the following ways

A

on average, TCR binds antigen with much lower affinity that does Ig molecule (or B cell)

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7
Q

both CD28 and CTLA-4 receptors on t cells that are critical for regulating t cell activation. which one of the following ways does CD28 differ from CTLA-4

A

CD28 expressed on niave t cells and CTLA-4 expressed on activated t cells

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8
Q

name a type of antigen recognized by antibodies that is also recognized by t cell receptors

A

peptide fragments

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9
Q

which of the following best describes a condition that leads to negative selection during t cell development in the thymus

and positive selection

A

negative selection: cell strongly recognizes peptide bound to MHC molecule

positive: cell WEAKLY recognizes peptide bound to MHC molecule

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10
Q

the cytokine IL-2 is the principle growth factor for what type of cells

A

T cells

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11
Q

D 2023
what signal would stimulate dendritic cell to produce B7 molecules

A

peptidoglycan binding to TLR

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12
Q

what additional mechanism is required for CD4 effector t cell bound to an MHC class II molecule plus antigen on macrophage to activate macrophage killing function

A

CD40 ligand on T cell binding to CD40 on macrophage

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13
Q

what is NOT a property of memory T lymphocytes elicited in response to particular microbe

A

restricted to residing in lymphoid organs

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14
Q

D 2023
activated macrophages perform all of the following functions except

A

reduce expression of MHC molecules

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15
Q

D 2023
which pair of molecules is a component of cytolytic T lymphocyte CTL granules and is important in the mechanism on CTL killing of target cells?

A

perforin and granzyme B

DEAL WITH CD8!!!

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16
Q

D 2023
which subset of CD4 helper T lymph. activate macrophages to kill phagocytosed microbes

A

Th1

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17
Q

what types of pathogens are the main target of the Th-17 subset of CD4 effector T cells

A

extracellular bacteria and fungi

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18
Q

what pathogens evade cell-mediated immunity by inhibiting phagosomal-lysosomal fusion

A

mycobacteria

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19
Q

which of the following events doesnt occur within germinal center

A

iG gene V(D)J recombination

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20
Q

which of the following statements about Ig isotype switching is true
(2 right answers)

A

isotype switching only occurs in activated B cells

AND isotype switching involves recombination of V(D)J complex with downstream C region DNA and the deletion of intervening C region D

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21
Q

which of the following statements about humoral immune responses is true

(two right)

A

naive B cells are required for initiation of primary responses and memory B cells are required for initiation of secondary responses

antibody responses to bacterial polysaccharide antigens doesn’t require CD4 helper T cells

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22
Q

compared and contrast primary and secondary antibody responses

A

primary:
low affinity
high concen
IgM
all types of antigen
naive B cells

secondary:
high affinity
low concen
IGG, IGA, IGE
mostly protein antigens
actiavated B cells
reach peak levels quicker

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23
Q

which of the following binds to and is readily phagocytosed by mononuclear phagocytes and neutrophils

A

complement protein C3b bound to bacterium

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24
Q

classical pathway of complement system starts with recognition of antigen engaged antibodies by

A

complement C1 protein

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25
Q

D 2023
____is the enhancement of phagocytosis by binding IgG-coated microbes to Fc receptors on phagocytes

A

opsonization

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26
Q

D 2023
which of the following anatomic regions is normally protected from pathogens only by humoral immune repsonses and not by cell-mediated immune responses

A

intestinal lumen

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27
Q

central T lymphocyte tolerance

A

is induced when immature developing t cells in bone marrow or thymus encounter self antigens

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28
Q

peripheral t cell tolerance

A

results when mature naive t cells recognize antigen without B7-1 or B7-2 mediated costimulation

AND

to some antigens is induced when mature to cells recognize antigen and bind B7-1 or B7-2 via the inhibotry CTLA-4 receptor

AND

may be induced by persistent and repeated stimulation of lymphocytes by that antigen in tissues

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29
Q

D 2023
mechanism of central B lymphocyte tolerance is

A

receptor editing by expression of a new Ig V light chain

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30
Q

immunologic tolerance is defined as

A

unresponsiveness of the immune system to self antigens

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31
Q

which of the following is NOT a mechanism that pathogenic bacteria use to evade host immune system defenses??

which are

A

not: stable attachment to surface of host cells

are: promoters, gain/loss at 5’ ends, addition of sialic acid, capsule

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32
Q

which of the following is a function of LPS on bacteria cells

A

blocks access of membrane attack complex MAC to the bacterial plasma membrane

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33
Q

D 2023
give specific example of molecule on human cell that is recognized and bound by SRRPS

A

sialic acid

34
Q

D 2023
fibronectin is a host protein that helps mediate indirect attachment of which bacterium to host cells

A

staphylococcus aureus

35
Q

which of the following is NOT an example of a means by which pathogenic bacteria can cause death of human host cells either directly or indirectly
(2 right)

A

LPS activation of the complement system

AND
binding Fc portion of IgG by bacterial surface proteins

36
Q

D 2023
what is true about the ADP ribosylation function of some A-B toxins

A

ADP ribosylation inactivates a target protein of host cells

37
Q

what is the direct action of lipases, which sometimes are found as toxins encoded by pathogenic bacteria

A

break down cell
(typing)

38
Q

D 2023
which hypersens is caused by immune complexes, composed of circulating antigens and IgM or IgG antibodies that are deposited in vascular basement membranes

A

type III

39
Q

D 2023
over 90% of staphylococcus aureus strains are resistant to what bacteria

A

penicillin

40
Q

what role does catalase have for those pathogenic bacteria that express it

A

removes hydrogen peroxide produced by phagocytes

41
Q

degrades collagen, allowing bacteria to penetrate tissue

A

collagenase

42
Q

creates fibrin coat around bacteria, preventing phagocytosis

A

coagulase

43
Q

converts plasminogen to plasmin, dissolving fibrin clot AND cleaves C3b and IgG

A

staphlokinase

44
Q

what genus of gram-positive coccus contains one of the main causes of hospital acquired infections of the elderly and displays resistance to multiple antibiotics

A

Enterococcus faecalis (typing)

type of streptococuccus

45
Q

which of the following lists one or more virulence factors for streptocuccus pneumoniae

A

pneumolysin O
polysacchiarde capsule
IgA protease
a-hemolysis

46
Q

what is true about streptococcus pneumoniae

A

is an alpha-hemolytic, encapsulated bacterium

47
Q

what streptococcus pyogenes virulence factor binds to keratinocytes, fibrinogen, and complment control proteins?

A

protein M

48
Q

which of the following is true about infections by Neisseria meningitidis?

A

preventable by vaccine again capsular polysacchiardes for some meningiococcal strains

AND
transmitted by aerosol, gram negative

49
Q

the bacterial capsule is an important factor for what specific aspect Neisseria meningitidis infections?

A

intravascular survival

50
Q

which of the following is a feature of infections caused by a breach in the gut wall

A

host production of thick fibrin capsule at infection site decreases blood flow into area

AND

abscess formation initiates with a mixed population of bacteria spilled into abdomen

51
Q

bacteroides fragillis is the most frequently isolated bacterium from abscesses caused by intestinal bacteria. This is partly because

A

its ability to resist phagocytosis

ALSO has catalase and superoxide dismutase

52
Q

D 2022
what cells do not display MHC-associated peptides on their cell surfaces for surveillance by and activation of class T of T cells

A

bacterial cells

53
Q

D 2022
which of the following statements about the antigen-presenting function of macrophages is correct

A

macrophages become activated by the helper T cells to which they present microbial peptides, and as a result of this activation they become efficient at killing the microbes

54
Q

which of the following is the main criterion that determines whether a protein is processes and presented via the class I MHC in an APC?

A

present in the cytosol

55
Q

D 2022
what mechanism within the germinal center contributes the most to creation of antibody molecules with higher and higher affinity for an antigen

A

addition and deltion of nucleotides during joinging of V,D, and J gene segments

56
Q

which subset of CD4 helper T lymphocytes activate eosinophils to kill helminths

A

Th2

57
Q

what mechanism do mycobacteria employ to survive within phagocytic cells? typing

A

inhibit fusion of phagosomal-lysosomal complex

58
Q

in 1890, emil von bhering ———

two right

A

passive immunity

Diphtheria-specific antibodies in the transferred serum neutralized bacillus toxins and promote bacterial elimination by innate effector cells

59
Q

The current SAR-CoV-2 vaccine——–

and this question have the same answer

most effective vaccines that are currently in widespread use are specific for pathogenic viruses, and the immunity induced—

A

the antibodies bind extracellular viral particles and prevent them from infecting cells

60
Q

failure of self-tolerance is the cause of what type of disease

A

autoimmune disease

61
Q

what is the most important costimulator for naive T cells

A

B7 ligand

62
Q

D 2022
what mechanism draws naive T cells out of lympnodes if they do not recognize an antigen in the lymph node

A

increased expression of S1P receptor by naive t cells in lymphnode

63
Q

D 2022
which of the following is not a mechanism used by bacteria to survive inside phagocytes

A

increasing CAMP levels in extracellular environment

64
Q

gram-negative bacteria often bids to host cells by

A

bacteria fimbriae proteins interacting with host cell glycolipids

65
Q

which of the following is a mechanism that pathogenic bacteria use to envade host immune system defenses?

few right answers

A

addition of sialic acid to LPS

capsule
gain/loss of repeat seq at 5’ ends
gene promoters

66
Q

xthe translocated INTIMIN receptor TIR mediates attachment to host cells for which bacterium

A

E. coli
enteropathogenic E. Coli

67
Q

LPS

A

causes fever in the host organism
AND
blocks access to MAC to bacterial plasma membrane
AND
activates the complement cascade in the host organism

68
Q

shiga toxin

A

removes a specific adenine base from 28S rRNA stopping translation

69
Q

what is the effect of collagenases when they are toxins encoded by pathogenic bacteria
typing

another question like this was:
give an example of a bacterial exotoxin that acts outside a host cell to help microbes spread through tissue

A

they degrade collagen and allow bacteria to enter host cell or penetrate host tissues

COLLAGENASE

70
Q

what organism causes scaled skin syndrome

A

staphylococcus aureus

71
Q

D 2022
what is true about rheumatic fever

A

causes myocarditis in susceptible individuals

72
Q

which of the following is NOT true regarding streptocuccus pyogenes M protein

A

anti-M protein antibodies are not produced during an infection by streptococcus pyogenes

73
Q

bacteroides fragilis is a strict anaerobe but is oxygen resistant because among its other properties it possesses

A

catalase and superoxide dismutase

74
Q

D 2021
most t lymphocytes have a duel specificity for which one of the following pairs of molecules (i.e. the t lymphocytes recognize both molecules of the pair?)

A

a particular allelic form of a MHC molecule and a peptide bound to the MHC molecule

75
Q

D 2021
all of the following protein-protein interactions are involved in activation of naive helper t cells by APC ExCEPT:

A

cd40L and Cd40 (these activate macrophages)

  1. B7 and Cd28
  2. peptide-MHC on APC to TCR on t cell
  3. Cd4 on t cell to nonpolymorphic of class II on apc
76
Q

helper T cell response to protein antigen requires participation of antigen presenting cells that express which of the following types of molecules

A

class II MHC and costimulators

77
Q

what role does protein A play for staphlococcus auereus

A

competes with neutrophils for binding of Fc part of IgGs

78
Q

scarlet fever is caused by what organism

A

streptococcus pyogenes

79
Q

which of the following is associated with neisseria gonorrhoeae

A

asymptomatic
gram negative
no capsule
no vaccine

80
Q

D 2021
what is true about antigenic variation involving the pilin protein of neisseria gonorrhoeae

A

involves recombination between silent and expressed copies of pilin gene

81
Q
A

microbiology exam 2 (14 decks)

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