all exams Flashcards by Madyson mccullick

APCs perform which of the following functions in adaptive immune responses

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

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which one of the following statements about dendritic cells is true

immature dendritic cells are ubiquitously present in skin and mucosal tissues

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

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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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?

only present with vesicular compartment of the APC during processing

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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

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

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

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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

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

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

peptide fragments

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

and positive selection

negative selection: cell strongly recognizes peptide bound to MHC molecule

positive: cell WEAKLY recognizes peptide bound to MHC molecule

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

T cells

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

peptidoglycan binding to TLR

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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

CD40 ligand on T cell binding to CD40 on macrophage

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

restricted to residing in lymphoid organs

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D 2023
activated macrophages perform all of the following functions except

reduce expression of MHC molecules

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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?

perforin and granzyme B

DEAL WITH CD8!!!

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

Th1

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

extracellular bacteria and fungi

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

mycobacteria

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which of the following events doesnt occur within germinal center

iG gene V(D)J recombination

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

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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which of the following statements about humoral immune responses is true

(two right)

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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compared and contrast primary and secondary antibody responses

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

complement protein C3b bound to bacterium

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

complement C1 protein

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

opsonization

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

intestinal lumen

central T lymphocyte tolerance

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

peripheral t cell tolerance

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

D 2023 mechanism of central B lymphocyte tolerance is

receptor editing by expression of a new Ig V light chain

immunologic tolerance is defined as

unresponsiveness of the immune system to self antigens

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

not: stable attachment to surface of host cells are: promoters, gain/loss at 5' ends, addition of sialic acid, capsule

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

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

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

sialic acid

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

staphylococcus aureus

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)

LPS activation of the complement system AND binding Fc portion of IgG by bacterial surface proteins

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

ADP ribosylation inactivates a target protein of host cells

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

break down cell (typing)

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

type III

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

penicillin

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

removes hydrogen peroxide produced by phagocytes

degrades collagen, allowing bacteria to penetrate tissue

collagenase

creates fibrin coat around bacteria, preventing phagocytosis

coagulase

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

staphlokinase

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

Enterococcus faecalis (typing) type of streptococuccus

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

pneumolysin O polysacchiarde capsule IgA protease a-hemolysis

what is true about streptococcus pneumoniae

is an alpha-hemolytic, encapsulated bacterium

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

protein M

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

preventable by vaccine again capsular polysacchiardes for some meningiococcal strains AND transmitted by aerosol, gram negative

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

intravascular survival

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

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

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

its ability to resist phagocytosis ALSO has catalase and superoxide dismutase

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

bacterial cells

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

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

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?

present in the cytosol

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

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

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

Th2

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

inhibit fusion of phagosomal-lysosomal complex

in 1890, emil von bhering --------- two right

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

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---

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

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

autoimmune disease

what is the most important costimulator for naive T cells

B7 ligand

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

increased expression of S1P receptor by naive t cells in lymphnode

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

increasing CAMP levels in extracellular environment

gram-negative bacteria often bids to host cells by

bacteria fimbriae proteins interacting with host cell glycolipids

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

addition of sialic acid to LPS capsule gain/loss of repeat seq at 5' ends gene promoters

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

E. coli enteropathogenic E. Coli

LPS

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

shiga toxin

removes a specific adenine base from 28S rRNA stopping translation

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

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

what organism causes scaled skin syndrome

staphylococcus aureus

D 2022 what is true about rheumatic fever

causes myocarditis in susceptible individuals

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

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

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

catalase and superoxide dismutase

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

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

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

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

class II MHC and costimulators

what role does protein A play for staphlococcus auereus

competes with neutrophils for binding of Fc part of IgGs

scarlet fever is caused by what organism

streptococcus pyogenes

which of the following is associated with neisseria gonorrhoeae

asymptomatic gram negative no capsule no vaccine

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

involves recombination between silent and expressed copies of pilin gene

all exams Flashcards

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