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Immunology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

The first line of defense against microorganisms that infect the body is referred to as _____.

A

innate immunity

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2
Q

Which of the following pairs is mismatched?

a. innate immunity: highly specialized defenses
b. secondary immune response: immunological memory
c. hematopoiesis: bone marrow
d. phagocytosis: uptake and killing of microbes
e. lymphocyte recirculation: continuous transport between blood and lymph

A

innate immunity: highly specialized defenses

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3
Q

When effector lymphocytes secrete _____, an inflammatory response ensues.

A

Cytokines

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4
Q

The thin layer of cells that makes up the interior lining of the blood vessels is called the _____.

A

Endothelium

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5
Q

Identify the incorrect statement regarding hematopoiesis.

a. Hematopoiesis is a continuous process that occurs throughout one’s lifetime.
b. The location for hematopoiesis differs with age.
c. Self renewal is necessary to replenish the supply of hematopoietic stem cells.
d. Most hematopoiesis occurs in the bone marrow after birth.
e. Leukocytes, but not erythrocytes, must go through hematopoiesis in order to develop.

A

Leukocytes, but not erythrocytes, must go through hematopoiesis in order to develop.

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6
Q

Effector cells that secrete antibodies are known as _____.

A

Plasma Cells

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7
Q

The _____ is (are) the lymphoid organ(s) that filter(s) the blood.

A

Spleen

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8
Q

_____ cells persist long after an individual has been vaccinated.

A

Memory

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9
Q

In most cases, adaptive immune responses rely on the initial activation of _____ in secondary lymphoid tissue:

A

B-Cells

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10
Q

All of the following statements are characteristic of secondary immune responses except _____.
a. Secondary immune responses are activated when primary immune responses fail to completely eradicate an infection.
b. Secondary immune responses are restricted to adaptive immune responses.
c. Memory cells are activated rapidly during secondary immune responses.
d. Secondary immune responses are orders of magnitude greater than primary immune responses.
e. During a secondary immune response to a booster vaccine, it is possible to experience a primary
immune response to an unrelated vaccine component encountered for the first time.

A

Secondary immune responses are activated when primary immune responses fail to completely eradicate an infection.

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11
Q

An example of an antimicrobial peptide that protects epithelial surfaces from pathogens is _____.

A

Defensin

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12
Q

Which of the following statements regarding neutrophils is false?

a. Neutrophils are mobilized from the bone marrow to sites of infection when needed.
b. Neutrophils are active only in aerobic conditions.
c. Neutrophils are phagocytic.
d. Neutrophils form pus, which comprises dead neutrophils.
e. Dead neutrophils are cleared from sites of infection by macrophages.

A

Neutrophils are active only in aerobic conditions.

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13
Q

Primary lymphoid tissues are the sites where lymphocytes _______, whereas secondary lymphoid tissues are the sites where lymphocytes _______.

A

develop and mature; become stimulated

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14
Q

Which of the following pairs is mismatched?

a. lymphocytes: innate immune response
b. natural killer cell: kills virus-infected cells
c. macrophage: phagocytosis and killing of microorganisms
d. erythrocyte: oxygen transport
e. eosinophil: defense against parasites.

A

lymphocytes: innate immune response

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15
Q

A term generally used to describe all white blood cells is _____.

A

leukocytes

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16
Q

Examples of granulocytes include all of the following except:

a. neutrophil
b. monocyte
c. basophil
d. eosinophil
e. All of the above are examples of granulocytes.

A

monocyte

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17
Q

The most abundant type of leukocyte in human peripheral blood is the _____.

A

Nuetrophill

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18
Q

Which of the following statements is false?
a. During human development, hematopoiesis takes place at different anatomical locations.
b. The hematopoietic stem cell gives rise to white blood cells, but a different stem cell is the progenitor
of red blood cells.
c. Hematopoietic stem cells are self-renewing.
d. Platelets participate in clotting reactions to prevent blood loss.
e. Megakaryocytes do not circulate and reside only in the bone marrow.

A

The hematopoietic stem cell gives rise to white blood cells, but a different stem cell is the progenitor
of red blood cells.

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19
Q

Vaccination is best described as prevention of severe disease by _______.

A

prior exposure to an infectious agent in an attenuated or weakened form

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20
Q

Which of the following explains why immunity to influenza may appear to be relatively short-lived?

A

New influenza variants able to escape previous immunity appear regularly.

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21
Q

Which of complement pathway(s) becomes activated soonest after an initial infection?

A

The alternative pathway

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22
Q

_____ are soluble complement fragments that mediate localized and systemic inflammatory responses.

A

anaphylatoxins

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23
Q

Although activation of the three different pathways (alternative, lectin, and classical) of complement activation converge involves different components, the three pathways converge on a common enzymatic reaction referred to as complement fixation. The reaction involves the cleavage of C3 into C3a and C3b and the covalent bonding of C3b to the pathogen surface.

A

true

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24
Q

The enzyme responsible for cleaving C3 into C3a and C3b is called C3 convertase, and it differs in composition depending on the particular complement pathway. The classical and lectin pathways use the classical C3 convertase (C3bBb), whereas the alternative pathway uses the alternative convertase (C4b2a).

A

False -

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25
Q

The steps that take place when a bacterium is opsonized via C3b:CR1 interaction between the bacterium and a resident macrophage in tissues are the following: (1) The CR1 on the macrophage can bind to C3b that is coating a bacterial surface after complement activation, and the macrophage then engulfs the bacterium through receptor-mediated endocytosis. (2) The macrophage membrane invaginates and forms an intracellular vesicle called a phagosome. (3) The phagosome fuses with a lysosome to form a phagolysosome, where toxic mediators and degradative enzymes are localized. (4) The bacterium is destroyed.

A

True

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26
Q

Regarding the three pathways of complement: (1) The classical pathway requires an activating surface of a pathogen, which stabilizes complement components. (2) The lectin pathway requires the presence of mannose-binding lectin, an acute-phase protein made by the liver in response to interleukin-6 (IL-6) (secreted by activated macrophages) and which accumulates in plasma during infection. (3) The alternative pathway is activated in two ways, either by the presence of antibody bound to the surface of the microorganism (for example IgM bound to lipopolysaccharide of Gram- negative bacteria) or by the presence of C-reactive protein bound to a bacterium.

A

False

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27
Q

Only the classical pathway is considered part of the adaptive immune response because of the requirement for antibody. However, the classical pathway is also considered part of innate immunity because of the ability of C-reactive protein, an acute-phase protein, to activate it. The other two pathways are considered part of innate immunity because they are initiated independently of antibody.

A

True

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28
Q

Which of the following does not accurately describe complement components?

a. soluble proteins
b. made by the spleen
c. located in extracellular spaces
d. some function as proteases once activated
e. activated by a cascade of enzymatic reactions

A

Made by spleen

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29
Q

A genetic deficiency of C3 leads to a type of immunodeficiency characterized by recurrent and severe infections. C3 is a key element in the initiation of the complement cascade in all three pathways of complement activation, namely the alternative, lectin, and classical pathways. Its cleavage into C3a and C3b occurs early in the complement cascade. C3a acts as an inflammatory mediator and recruits inflammatory cells to the site of infection. C3b becomes fixed to the pathogen surface and facilitates the opsonization of pathogens by phagocytes and the assembly of complement components for perforation of the pathogen membrane. In the absence of C3, all three pathways of complement activation would be arrested and extracellular pathogens would escape immune detection until adaptive immune mechanisms develop fully many days later.

A

True

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30
Q

Which of the following is the membrane-bound form of C3 convertase of the alternative pathway of complement activation?

A

C3bBb

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31
Q

The alternative C3 convertase on pathogen cell surfaces is formed by spontaneous hydrolysis of C3 without cleavage exposes its highly reactive thioester bond, forming iC3. Factor B binds to iC3, is cleaved by factor D, and consequently releases a small fragment called Ba. The larger fragment, Bb, remains associated with iC3 to form iC3Bb, a soluble C3 convertase, which cleaves C3 into C3a and C3b. The reactive thioester bond of C3b is attacked by R–OH and R–NH2 groups on the surface of the pathogen, where it becomes anchored and binds to factor B. Factor D then cleaves factor B, releasing fragment Ba and forming C3bBb on the pathogen surface. The alternative C3 convertase on pathogen cell surfaces is stabilized by Factor P (properdin) binds to C3 convertase (C3bBb) bound to the pathogen surface, and inhibits the proteolytic degradation of C3bBb. This stabilizes the C3 convertase and enhances the rate of C3b deposition on the pathogen surface.

A

True

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32
Q

During the formation of the membrane-attack complex, it is important to expose the hydrophobic sites of C7 and C8, because these sites enable anchoring of these two complement components into the membrane of the pathogen. Once anchored in the membrane, the hydrophobic site of C8 facilitates C9 polymerization, which completes the formation of the membrane-attack complex.

A

True

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33
Q

The plasma proteins that counteract the activity of factor P by inactivating C3 convertase through the cleavage of C3b are _____.

A

factor H and factor I

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34
Q

The membrane-bound proteins on human cells that dissociate and inactivate alternative C3 convertase to avoid complement activation are _____.

A

decay-accelerating factor and membrane cofactor protein

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35
Q

Anaphylatoxins C3a and C5a contribute physiologically to inflammation during complement activation. G-protein-coupled receptors for the anaphylatoxins C3a and C5a are found on phagocytes, mast cells, and the endothelial cells of blood vessel walls. Anaphylatoxin bound to mast cells causes them to degranulate, releasing inflammatory mediators such as histamine and leading to increased vascular permeability. Through their action on endothelial cells, anaphylatoxins exert vasoactive effects on blood vessels, contributing to increased vascular permeability and increased blood flow, which facilitate the extravasation of plasma proteins, such as complement proteins and antibodies, and the recruitment of cells to infected tissues through increased adherence and chemotaxis. Phagocytic activity is enhanced by anaphylatoxins, which bring about increased levels of CR1 and CR3 and microbicidal activity. All these activities enhance inflammation.

A

True

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36
Q

Which of the following polymerizes to form a transmembrane channel that compromises the integrity of cell membranes?

A

C9

37
Q

Which of the following does not describe the actions of the coagulation system?

A

enhancement of dissemination of microbes into lymphatics and bloodstream

38
Q

Damage to tissues triggers a cascade of plasma proteins involving bradykinin and is known as _____.

A

the kinin system

39
Q

Which of the following complement components is an opsonin that binds to complement receptor 1 (CR1) on macrophages?

A

C3b

40
Q

Lectins recognize microbial _____.

A

Carbohydrates

41
Q

Macrophages bear on their surface receptors for all of the following except _____.

a. mannose and glucans
b. C3b
c. muramyl dipeptide and CpG-rich bacterial DNA
d. lipopolysaccharide
e. lipoteichoic acid

A

muramyl dipeptide and CpG-rich bacterial DNA

42
Q

_____ are structurally similar membrane-bound proteins that aid in the adhesion between various types of human cell.

A

Integrins

43
Q

All of the following cytokines induce fever except _____.

a. IL-12
b. IL-6
c. IL-1
d. TNF-alpha
e. None of the above

A

IL-12

44
Q

Which of the following is not associated with mobilization of neutrophils to infected tissue?

a. TNF-alpha production by macrophages
b. upregulation of selectins on blood vessel endothelium
c. interferon response
d. generation of a CXCL8 gradient
e. extravasation across endothelium
f. proteolysis of basement membrane of blood vessels.

A

Interferon response

45
Q

The pH of the phagosome increases following phagocytosis because _____.

A

hydrogen ions are eliminated by the activity of NADPH oxidase and superoxide dismutase

46
Q

The name given to cytokines that recruit cells to move towards areas of inflammation is _____.

A

Chemokines

47
Q

In common with Toll-like receptors, NOD-like receptors also contain _____ that is/are used for pathogen-recognition of microbial ligands.

A

LRR’s (leucine-rich repeat regions)

48
Q

Identify which of the following receptors does not lead to nuclear translocation of NFkB through an activated IKK intermediate.

A

All of the above receptors culminate in nuclear translocation of NFkB through an activated IKK
intermediate.

49
Q

_____ help to prevent systemic bacterial dissemination by producing chromatin structures loaded with antimicrobial substances.

A

Neutrophil extracellular traps (NETs)

50
Q

_____ is/are needed to minimize the damaging effects to neighboring host cells during a respiratory burst.

A

Catalase activity

51
Q

Toll-like receptors differ from scavenger receptors in that they _____.

A

mediate signal transduction pathways, causing cytokine production

52
Q

All of the following statements regarding Toll-like receptors are true except _____.

A

The cytoplasmic signaling domain contains a variable number of leucine-rich repeat regions (LRRs)

53
Q

_____ binds to and retains NFkB in the cytosol.

A

IkB

54
Q

All of the following are correct in reference to type I interferons except _____.

A

The receptor for type I interferons is abundant in the cytosol

55
Q

Which of the following does not describe a safety mechanism to ensure that only infected cells are attacked by NK cells?

A

No single receptor–ligand interaction induces cytotoxicity, but instead many combinations of
receptor–ligand interactions influence the decision to kill or not to kill a target cell.

56
Q

_____ is/are cytokine(s) produced by both macrophages and dendritic cells that promotes the proliferation, differentiation, and survival of NK cells.

A

IL-12 & IL-15

57
Q

An adaptor protein in the inflammasome is required to link _____ to the NOD-like receptor NLRP3.

A

procaspase-1

58
Q

What is the name given to the earliest intracellular vesicle that contains material opsonized by macrophages?

A

phagosome

59
Q

The first domain of the TLR is an extracellular domain, also known as the pathogen-recognition domain, which contains a hydrophobic, leucine-rich repeat region (LRR) forming a horseshoe-shaped structure that binds specifically to arrays on microbial surfaces. The second domain of the TLR is the cytoplasmic signaling domain, also known as the Toll interleukin receptor (TIR) domain, which facilitates the transmission of information to the interior of the cell.

A

True

60
Q

When TLR3 on the surface of macrophages is bound to its LPS ligand, a signal transduction cascade is initiated that mediates signaling between the cell surface and the nucleus. The macrophage in turn begins to express particular genes encoding cytokines and adhesion molecules that are needed to induce a state of inflammation in the infected tissue.

A

False

61
Q

Which of the following adaptor proteins participates in the activation pathway induced through either TLR3 or TLR4 that culminates in the synthesis of type I interferons?

A

TRIF

62
Q

Which of the following properties is common to macrophages and neutrophils in an uninfected individual?

A

ability to phagocytose

63
Q

Which of the following best describes an endogenous pyrogen?

A

cytokines made by the host that increase body temperature correct

64
Q

During inflammation, host tissue may be damaged owing to the release of toxic oxygen derivatives produced by activated macrophages and neutrophils. Toxic oxygen species including superoxide, hydrogen peroxide, singlet oxygen, hydroxyl radical, hypohalite, and nitric oxide are produced during the respiratory burst in macrophages and neutrophils. Simultaneous extraphagosomal production of enzymes that neutralize these compounds occurs. Specifically, superoxide dismutase metabolizes superoxide to hydrogen peroxide, which is further metabolized by catalase to innocuous water and molecular oxygen.

A

True

65
Q

The name given to a fully activated and differentiated B cell that secretes antibody is __________________.

A

plasma cell

66
Q

The five isotypes of immunoglobulin differ from each other in their _____.

A

heavy-chain constant regions

67
Q

The immunoglobulin heavy-chain gene consists of _______ segments, whereas the immunoglobulin light-chain gene consists of _______ segments.

A

VDJ; VJ

68
Q

Which of the following describes two recombination signal sequences required for a permitted somatic recombination event?

a. VH 7-12-9::9-23-7 JH
b. Vλ7-23-9::9-23-7 Jλ
c. DH 7-12-9::9-23-7 JH
d. Vκ7-12-9::7-23-9 Jκ
e. VH 9-23-7::7-12-9 DH

A

DH 7-12-9::9-23-7 JH

69
Q

Which of the following corresponds to the antigen-binding site of immunoglobulins?

A

VH:VL

70
Q

Another term commonly used to describe hypervariable loops is ___________.

A

complementarity-determining regions (CDR)

71
Q

All of the following are utilized in the binding of antibodies to antigens except:

a. interchain disulfide bonds
b. hydrogen bonding
c. hydrophobic interactions
d. electrostatic forces (salt bridges)
e. van der Waals interactions

A

interchain disulfide bonds

72
Q

With the exception of B cells, all other cells of the body have the immunoglobulin genes in the ______________.

A

Germ-line configuration

73
Q

Indicate which of the following statements is false.

a. Light chains contain V and J segments, whereas heavy chains contain V, D, and J segments.
b. The Vκ gene segments are duplicated in about 50% of the human population.
c. All immunoglobulin loci include a leader sequence.
d. On the heavy-chain locus, V rearranges to D first, and then J joins the combined VD sequence.
e. Immunoglobulin heavy-chain loci undergo two rounds of somatic recombination, whereas light-chain loci undergo only one.

A

On the heavy-chain locus, V rearranges to D first, and then J joins the combined VD sequence.

74
Q

Which of the following enzymes facilitates the process of affinity maturation?

a. DNA ligase
b. V(D)J recombinase
c. terminal deoxynucleotidyl transferase
d. activation-induced cytidine deaminase (AID)
e. exonuclease

A

activation-induced cytidine deaminase (AID)

75
Q

The process of gene rearrangement in immunoglobulin and T-cell receptor genes is called _________________.

A

Somatic Recombination

76
Q

Junctional diversity during gene rearrangement results from the addition of __________________.

A

P & N nucleotides

77
Q

A circulating B cell that has never before encountered antigen expresses _____ on the cell surface.

A

IgM & IgD

78
Q 
All of the following processes occur in mature B cells after antigen encounter except: a. alternative splicing
2
b. affinity maturation
c. proliferation
d. somatic recombination 
e. isotype switching
A

somatic recombination

79
Q

Which of the following does not describe B-cell receptors?

a. B-cell receptors are membrane-bound and secreted.
b. B-cell receptors consist of a variable region and a constant region.
c. B-cell receptors lack specificity and can bind to a number of different antigens.
d. B-cell receptors possess specificity and can therefore bind only to unique epitopes.
e. B cell receptors undergo affinity maturation as a consequence of somatic hypermutation.

A

B-cell receptors lack specificity and can bind to a number of different antigens

80
Q

Which of the following determines the isotype of an immunoglobulin?

a. the composition of the hypervariable regions
b. whether the immunoglobulin is membrane-bound or secreted
c. its light chain
d. its heavy chain
e. the composition of the cytoplasmic tails of Igα and Igβ

A

its heavy chain

81
Q

The highest degree of diversity resulting from somatic recombination is concentrated ____________ of the VH and VL domains, whereas the point mutations caused by somatic hypermutation are found ____________.

A

in CDR3; throughout the V region

82
Q

As an adaptive immune response progresses, the production of variant antibodies that compete more effectively for antigen occurs, and B cells producing these antibodies are preferentially selected on the basis of their improved binding to antigen. This phenomenon is referred to as _______.

A

affinity maturation

83
Q

Which of the following statements about the production and use of monoclonal antibodies is incorrect?
a. Production of monoclonal antibodies requires a purified form of antigen.
b. A monoclonal antibody has specificity for only one epitope of an antigen.
c. B cells are fused with a tumor cell called a myeloma, to immortalize the resulting hybridoma.
d. Monoclonal antibodies made in mice have limited therapeutic potential.
e. Humanized monoclonal antibodies reduce complications associated with using mouse monoclonal
antibodies.

A

Production of monoclonal antibodies requires a purified form of antigen.

84
Q

The mutational mechanism that results in the production of antibodies that bind antigen with higher affinity is called _____.

A

somatic hypermutation

85
Q

The process of _____ results in change in the constant region of the heavy-chain of antibodies, causing a change in the effector function and transport properties of antibodies.

A

isotype switching

86
Q

The process used to produce either surface or secreted forms of the immunoglobulin heavy chain is called __________________.

A

alternative RNA processing

87
Q

Which immunoglobulin is transported most efficiently across mucosal epithelium?

A

IgA

88
Q

A newborn derives passive immunity from its mother as a result of placental transfer of _____ during pregnancy.

A

IgG

89
Q

The process of _____ results in the amplification of particular B cells with specificity for antigen.

A

clonal Selection

Immunology (3 decks)

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