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Effector mechanisms of humoral immunity Flashcards

1
Q

Effector functions of antibodies

A
  1. neutralization of microbes/toxins
  2. opsonization/phagocytosis of microbes
  3. antibody-dependent cellular cytotoxicity
  4. complement: phagocytosis, inflammation, lysis
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2
Q

Main function of antibodies

A

neutralize and eliminate infectious microbes and microbial toxins

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3
Q

antibodies are produced by what ?

A
  1. plasma cells in peripheral (secondary) lymphoid
  2. inflamed tissues
  3. bone marrow
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4
Q

where do antibodies perform their effector functions ?

A

distant from their production

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5
Q

effector functions of antibodies are mediated by …

A

Fc regions of Ig molecules & different Ig heavy chain isotypes

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6
Q

the effector functions of antibodies that are mediated by the Fc regions are triggered by what?

A

binding of antigens to the variable regions

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7
Q

mechanism of polio vaccine

A

neutralization of virus by IgG or by mucosal IgA antibody

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8
Q

mechanism of tetanus, diphtheria vaccine

A

neutralization of toxin by systemic IgG antibody

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9
Q

mechanism of hep A and hep B vaccine

A

neutralization of virus by mucosal IgA or systemic IgG antibody

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10
Q

mechanism of pneumococcal pneumonia, haemophilus influenzae, neisseria meningitidis vaccine

A

opsonization & phagocytosis mediated by IgM and IgG antibodies, directly or secondary to complement activation

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11
Q

Functions of IgG

A
  1. opsonization of antigens for phagocytosis via macrophages/neutrophils
  2. activation of classical complement
  3. antibody-dependent cell-mediated cytotoxicity by NK cells
  4. neonatal immunity (maternal antibodies cross placenta)
  5. feedback inhibition of B cell activation
  6. neutralization of microbes
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12
Q

Function of IgM

A

activation of the classical pathway of complement

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13
Q

Functions of IgA

A
  1. Mucosal immunity through the lumen of the gastrointestinal and respiratory tracts
  2. Neutralization of microbes and toxins in lumens of mucosal organs
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14
Q

Functions of IgE

A
  1. Mast cell degranulation (immediate hypersensitivity reactions)
  2. Eosinophil-mediated defense against helminths
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15
Q

FcRN receptor

A

pH-dependent that has an increased half-life and transports maternal IgG to fetus

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16
Q

FcγRIIA, FcγRIIB & FcγRIIC receptors has ___ affinity for immunoglobulin

A

Low

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17
Q

Inhibitory Fcy receptor (w/ low affinity)

A

FcγRIIB

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18
Q

Activating Fcy receptors

A
  1. FcyRI
  2. FcyRIIA/C
  3. FcyRIII-A
  4. FcryRIII-B
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19
Q

Which activating Fcy receptor have high affinity for immunoglobulin?

A

FcyRI

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20
Q

Which activating Fcy receptor have low affinity for immunoglobulin?

A
  1. FcyRIIA/C
  2. FcyRIII-A
    3.FcγRIII-B
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21
Q

FcyRI activates

A

CD64

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22
Q

FcyRIIA/C activates …

A

CD32

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23
Q

FcyRIII-A and FcyRIII-B activates

A

CD 16

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24
Q

FcγRIIB inhibits

A

CD32

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25
Q

Select all that apply: Cell distribution of FcyRI (CD64)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

Macrophages, neutrophils and Eosinophils (MEN)

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26
Q

Select all that apply: Cell distribution of FcyRIIA (CD32)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

Platelets, Eosinophils, Neutrophils, Dendritic cells and Macrophages (PENDM)

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27
Q

Select all that apply: Cell distribution of FcyRIIB (CD32)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

B cells, Macrophages, Dendritic cells (BMD)

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28
Q

Select all that apply: Cell distribution of FcyRIIC (CD32)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

NK cells, Neutrophils and Macrophages (NKNM)

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29
Q

Select all that apply: Cell distribution of FcyRIIIA (CD16)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

NK cells, Macrophages, Dendritic cells (NKMD)

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30
Q

Cell distribution of FcyRIIIB (CD16)

A

Neutrophils

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31
Q

Affinity of FcεRI

A

High; binds IgE

32
Q

Affinity of FcεRII (CD23)

33
Q

Affinity of FcaR (CD89)

34
Q

Select all that apply: Cell distribution of FcεRI
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

Mast cells, basophils, eosinophils (Masbephils)

35
Q

Select all that apply: Cell distribution of FcεRII (CD23)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

B cells, eosinophils, Langerhans cells (BLangEphil)

36
Q

Select all that apply: Cell distribution of FcaR (CD89)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes

A

Neutrophils, Eosinophils, Monocytes (NEM)

37
Q

function of FcyRI (CD64)

A

phagocytosis; activation of phagocytes

38
Q

function of FcyRIIA (CD32)

A

phagocytosis; cell activation

39
Q

function of FcyRIIB (CD32)

A

feedback inhibition of various cellular responses

40
Q

function of FcyRIIC (CD32)

A

phagocytosis; cell activation

41
Q

function of FcyRIIIA (CD16)

A

antibody dependent cell mediated cytotoxicity

42
Q

function of FcyRIIIB (CD16)

A

phagocytosis (inefficient)

43
Q

function of FcεRI

A

cell activation (degranulation)

44
Q

function of FcεRII (CD23)

45
Q

function of FcaR (CD89)

A

cell activation

46
Q

What is the role of Fc receptors in antibody-coated (opsonized) particles?

A

They stimulate the microbicidal activities of phagocytes

47
Q

True or False: Antibodies block the infectivity of microbes by binding to the microbes and sterically hindering interactions with cellular receptors.

48
Q
  1. True or False: Attachment of antigen-complexed Ig to phagocyte Fc receptors does not deliver signals that stimulate the microbicidal activities of phagocytes.
49
Q

Which statement is true regarding the role of antibodies in defense against extracellular microbes and microbial toxins?
a. Antibodies destroy microbes by directly attacking them.
b. Antibodies block the infectivity of microbes and toxins by binding to them and preventing interactions with cellular receptors.

A

Antibodies block the infectivity of microbes and toxins by binding to them and preventing interactions with cellular receptors.

50
Q

Which statement is false regarding Fc receptors and antibody-coated particles?
a. Fc receptors stimulate the microbicidal activities of phagocytes.
b. Different Fc receptors bind antibodies with the same affinities.
c. Fc receptors are specific for different subclasses of antibodies.

A

Different Fc receptors bind antibodies with the same affinities.

51
Q

Which of the following are true regarding the production of antibodies that protect against infection? (Select all that apply)

a.They are produced only upon the first exposure to microbial antigen

b.They may be generated by long-lived antibody-secreting cells

c.They can be produced by reactivation of memory B cells

A

B. They may be generated by long-lived antibody-secreting cells
C. They can be produced by reactivation of memory B cells

52
Q

Which arm of the adaptive immune system is primarily responsible for defense against extracellular microbes and microbial toxins?

A

humoral immunity

53
Q

What is the common endpoint for all three major pathways of complement activation?

54
Q

How are antibodies involved in blocking the infectivity of microbes and toxins?

A

By binding to and hindering interactions of microbes with cellular receptors

55
Q

True or False: The three major pathways of complement activation converge on a common pathway involving the formation of a membrane pore after the proteolytic cleavage of C5.

56
Q

why complement activation need to be regulated?

A
  1. Low-level complement activation goes on spontaneously and the result can damage normal cells and tissues.
  2. degradation products of complement proteins can diffuse to adjacent cells and injure them.
57
Q

Different regulatory mechanisms of complement activation

A
  1. Inhibition of the formation of C3 convertases in the early steps of complement activation.
  2. Break down and inactivate C3 and C5 convertases.
  3. Inhibition of the formation of the MAC in the late steps of the complement pathway.
58
Q

Which biologic functions are associated with the complement system? (Select all that apply)
a. Opsonization of organisms and immune complexes
b. Activation of inflammatory cells by proteolytic fragments
c. Cytolysis mediated by MAC formation
d. Enhancement of cellular immune responses
e. Solubilization and clearance of immune complexes

A

a. Opsonization of organisms and immune complexes
b. Activation of inflammatory cells by proteolytic fragments
c. Cytolysis mediated by MAC formation
e. Solubilization and clearance of immune complexes

59
Q

Which pathway of complement activation is initiated by circulating lectins binding to carbohydrates on pathogens?

A

c. Lectin pathway

60
Q

Which is a principal mechanism of innate immunity against extracellular bacteria?
a. Phagocytosis
b. Cell-mediated immunity
c. Cytotoxic T lymphocytes

A

Phagocytosis

61
Q

What is the major protective immune response against intracellular bacteria?
a. Innate immune response
b. B cell activation
c. Humoral immunity
d. Cell-mediated immunity

A

Cell-mediated immunity

62
Q

T/F Hereditary angioneurotic edema is caused by failure to regulate complement activation.

63
Q

PNH missing …

64
Q

t/f PNH increased sensitivity to complement lysis

65
Q

characteristic of PNH

A

hemoglobinuria (loss of iron)

66
Q

treatment of PNH

A
  1. Transfusion of packed red blood cells can replace lost cells.
  2. Androgens and recombinant erythropoietin are commonly used to accelerate erythropoiesis.
  3. Thrombotic complications are reduced by standard therapy, including heparin and maintenance doses of common anticoagulants.
  4. Iron loss is corrected by the administration of supplemental iron.
  5. To reduce complement activation, eculizumab can be used to block the activation of C5 and the generation of the MAC
67
Q

t/f Paroxysmal nocturnal hemoglobulinuria (PNH) is caused by lack of membrane-bound complement inhibitors.

68
Q

true/false Complement deficiencies in C2, alternative pathway components, or the membrane attack complex (MAC) increase the risk of life-threatening neisserial infections.

69
Q

Hereditary angioneurotic edema (HANE) is caused by

A

C1 INH deficiency

70
Q

treatment of HANE

A

Oral androgens, anabolic steroids, and antifibrinolytic agents

71
Q

treatment of HANE in case of acquired C1 INH deficiency

A

glucocorticosteroids

72
Q

alternative pathway activated by ….

A

microbial surfaces in the absence of antibody

73
Q

classical pathway activated by ….

A

antigen-antibody complexes

74
Q

lectin pathway activated by ….

A

circulating lectins binding to carbohydrates on pathogens

75
Q

Individuals with a …. deficiency usually have recurrent infections of the respiratory tract, gut, and
skin.

76
Q

t/f Life-threatening meningitis is associated with defects in properdin, factor H, factor I, and the
complement MAC.

A

true, which is why meningococcal vaccination is indicated to create high levels of protective
antibodies.

Immunology Exam 3 (7 decks)

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