6: Antibody structure Flashcards

1
Q

3 main functions of antibodies

A
  • opsonization
  • complement activation
  • neutralization
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2
Q

opsonization examples (2)

A
  • phagocytosis
  • eosinophil dumps toxic products to kill parasite
  • coating antigen with antibody enhances phagocytosis
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3
Q

complement activation

A

series of proteins activated by antibody binding to surface –> punch holes in bacteria
-inflammation and cell lysis

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4
Q

neutralization

A

secreting products onto virus/bacteria to block adhesion to mucosa

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5
Q

what is adaptive/acquired immunity

A

the specific response to antigenic challenge

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6
Q

what is adaptive immunity mediated by

A

antigen-specific lymphocytes and/or their products

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7
Q

5 steps of the immune response

A
  • innate immunity
  • early induced response
  • late adaptive response
  • protective immunity
  • immunological memory
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8
Q

steps of innate immunity

A

innate immunity –> infection –> recognition by non-specific effectors –> pathogen clearance

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9
Q

steps of early induced response

A

early induced response –> infection –> recruitment of effector cells –> activation of effector cells –> pathogen clearance

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10
Q

steps of late adaptive response

A

late adaptive response –> infection –> antigen transport to lymphoid organs –> recognition by native b and t cells –> clonal expansion of b and t cells –> pathogen clearance

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11
Q

steps of protective immunity

A

-protective immunity –> re-infection –> recognition by preformed antibody and effector t cells –> pathogen clearance

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12
Q

steps of immunological memory

A

immunological memory –> re-infection –> recognition by memory b and t cells –> rapid expansion to effector cells –> pathogen clearance

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13
Q

when does antibody production initiate

A

3-7 days after initial exposure if the innate immune processes fail to clear it rapidly

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14
Q

what are antibodies

A

antigen-specific products of b cells –> principal mediators of adaptive immunity

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15
Q

antibody structure

A
  • 2 identical heavy chains, 2 identical light chains
  • variable and constant regions
  • 2 binding sites on top of light chains
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16
Q

how do antibodies interact with antigens

A

non-covalently

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17
Q

how are antibodies divided into isotypes (classes)

A

different constant regions –> heavy chain weight gives different properties (heavy chain is the constant region)

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18
Q

types of antibodies made by b cells

A
  • different b cells make different antibodies

- a single b cell makes all the same antibodies

19
Q

how are distinct antibody regions determined

A

by protease digesion –> Fc portion contains heavy chain constant region, Fab portion contains the antigen binding site

20
Q

what are Fc and Fab

A
  • Fc: fragment of crystalization

- Fab: fragment of antigen binding

21
Q

how are different antibody regions defined

A
  • proteolytic digesion

- function

22
Q

where are antibodies assembled

A

in the b cell

23
Q

where does antigen binding occur

A

binding site at junction of variable heavy chain and variable light chain

24
Q

valency of antibodies

A

multivalent –> can bind 2 of the same epitopes on a single antigen or 2 of the same epitopes on different antigens

25
Q

types of antibody differences (3)

A
  • isotypic differences (IgG v IgA)
  • allotypic differences (different alleles but both IgG)
  • idiotypic differences (binding site differences)
26
Q

difference between b cell and mature plasma cell

A
  • b cell has antibodes on cell surface
  • plasma cell secretes antibodies
  • plasma cell is a b cell that secretes antibodies
27
Q

what immunoglobulin is always secreted first by a b cell

A

IgM

28
Q

what Ig are secreted onto mucosal surfaces and protected from degradation by binding to the J chain

A

IgM and IgA

29
Q

how are IgM and IgA secreted

A
  • IgM as a pentomer
  • IgA as a dimer
  • antigen specificity of antigen binding site is identical for both
30
Q

purpose of J chain

A

used to transport dimeric IgA across epithelial barriers to coat mucosal surfaces

31
Q

what does the variable region confer

A

epitope specificity

32
Q

what does the Ig constant region confer

A

functional capacity

33
Q

what does allelic exclusion result in

A

only 1 chromosome rearrangement per cell

34
Q

what is IgM known for

A

complement activity

35
Q

what is IgD known for

A

not fucking much

36
Q

what is IgG known for

A

basically everything (opsonization, crosses placenta, extravascular diffusion) –> phagocytosis

37
Q

what is IgA known for

A

mucosal –> crosses epithelium

38
Q

what is IgE known for

A

mast cell activation

39
Q

what are isotypes encoded by

A

a cluster of heavy chain genes

40
Q

what influence which isotype is expressed

A

cytokines

41
Q

consequences of inherited IgA deficiency

A

no antibodies on lung surface –> URI

42
Q

what connects variable and heavy chains together

A

hinge –> gives flexibility

43
Q

how is the region of the antibody gene that binds to the epitope generated

A

by a semi-random rearrangement of gene segments –> different exons for the antibody chains within each b cell (more variation = more things recognized)