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Immunology and Microbiology > Chapter 4 - B cell (Exam 3) > Flashcards

Chapter 4 - B cell (Exam 3) Flashcards

(97 cards)

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1
Q

Functions of antibodies

A
  1. Recognize and bind antigens
  2. Target bound antigen to other cells
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2
Q

Number of Ab molecules one can produce is limited by

A

Number of B cells

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3
Q

Before antigen binding

A

Ig is bound to B cell surface receptor

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4
Q

After antigen binding

A

B cell proliferates and differentiates into plasma cell
Secretes antibody

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5
Q

Different antibody structures

A

Light + Heavy
Variable + Constant

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6
Q

Fab fragment

A

Fragment antigen binding

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7
Q

Fc fragment

A

Fragment crystallizable

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8
Q

Proteolytic cleavage

A

Two Fab and one Fc

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9
Q

5 isotypes of heavy chains

A

IgG, IgM, IgD, IgA, IgE

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10
Q

Secreted as monomers?

A

IgG, IgD, and IgE

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11
Q

Secreted as monomer and dimer?

A

IgA

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12
Q

Secreted as pentamer?

A

IgM

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13
Q

What are the two isotypes of light chains?

A

kappa and lambda
each antibody has EITHER one

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14
Q

H and L chains arranged in

A

immunoglobulin domains

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15
Q

Differences in ____ lead to variability and different binding properties in light chains.

A

Loops

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16
Q

Globular

A

Soluble in aqueous environment
-hydrophilic aa out
-hydrophobic aa in

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17
Q

Immunoglobulin-like domain

A

present in other proteins as well
immunoglobulin superfamily

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18
Q

Hypervariable regions (HV)

A

major differences in aa sequences reside
Complementary determining regions (CDRs)

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19
Q

Framework regions (FR)

A

low variability in amino acid sequence

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20
Q

Types of antigen binding sites

A

Pocket
Shallow groove
Extended surface
Protrusion

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21
Q

Antigen binding sites

A

Non-covalent forces bind chemical groups in antigen to amino acids of Ab

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22
Q

Non-covalent forces

A
  1. electrostatic interactions
  2. hydrogen bonds
  3. van der waals forces
  4. hydrophobic interactions
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23
Q

what do antibodies recognize?

A

proteins, carbohydrates, glycoproteins, proteoglycans, glycolipids, etc

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24
Q

antibodies recognize _______________ on he outer surface

A

native structure

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25
B cell differentiates into a ___________ which secretes ____________
plasma cell antibody
26
epitope
antigenic determinant part of antigen to which antibody binds cluster of amino acids
27
antibodies are most effective at binding
surface epitopes
28
multivalent antigen
more than 1 epitope
29
antibody epitopes can be
linear or discontinuous
30
polyclonal antibody
different antibodies recognize different epitopes
31
monoclonal antibody
same antigens, same epitope
32
way to produce antibodies in research
immunize an animal, collect antisera from blood (pure) and produce polyclonal antibodies
33
monoclonal antibodies in research
B cells from mouse and tumor cells fused together select antigen specific hybdridoma and grow in large numbers
34
uses of antibodies in research
identify many unknown surface proteins monitor specific surface protein expression
35
flow cytometry
use of fluorescent antibodies to measure cell population in blood detect diseases
36
antibodies in the clinic are used to _______ how?
treat diseases inject mouse antibodies into deficient patients, prevent transplant rejection
37
modifications to mouse monoclonal antibodies to prevent human immune system attack
chimeric humanized human
38
chimeric modifications drug example
mouse V regions, human C region rituximab - lymphoma
39
humanized modifications drug example
mouse CDRs, all other sequences human omalizumab - allergic asthma
40
human modifications drug example
completely human antibody sequence antibody from mice to have human Ig genes adalimumab (HUMIRA)
41
another name for human modifications is
human hybridomas
42
ELISA
enzyme linked immunosorbent assay measures concentration of an antibody/antigen that can bind to an antibody
43
quantification of ELISA
absolute concentration or antibody titer
44
RIA
radioimmunoassay measures the concentration of an antibody/antigen that can bind an antibody
45
coombs test
tests for presence of antibodies and complement that can bind to RBCs results in red blood lysis/anemia
46
western blot
detects presence of a single protein in a complex mixture of proteins
47
immune system needs to generate a _______ population of antibodies that can recognize any pathogen at infection site and target it for destruction
diverse
48
what happens before antigen binding?
generate billions of B cells containing a surface immunoglobulin with a unique variable region
49
what happens after antigen binding?
secrete antibody modify variable region to bind more tightly switch heavy chain
50
why do we switch heavy chain after antigen binding?
to eliminate the pathogen most effectively
51
things that happen before antigen binding
somatic recombination junctional diversity combination of different heavy chains and light chains
52
antibodies cannot be _________ until they are __________
expressed rearranged
53
light chain variable region contains
variable (V) and joining (J) segments
54
heavy chain variable region contains
variable (V), joining (J) and diversity (D) segments
55
rearranged V, D and J segments encode for
CDR loops of antibody
56
do constant regions have to be rearranged?
NO BITCH!
57
which constant region determines the isotope of the antibody?
the closest one
58
somatic recombination
random rearranging of antibodies
59
how many rearrangements in light chains?
1 (V-J joining)
60
how many rearrangements in heavy chains?
2 (DJ, V-DJ joining)
61
enzyme responsible for the recombination of genes
VDJ recombinase
62
examples of recombination activating genes
RAG-1 and RAG-2
63
what is involved in the recombination of genes?
VDJ recombinase recombination activation genes DNA repair enzymes
64
junctional diversity
2 sets of new nucleotides are randomly added (P and N)
65
Severe Combined Immunodeficiency (SCID)
genetic deficiencies RAG enzymes B and T cells are not produced
66
3 contributions to antibody diversity
antibody DNA gene segments are randomly combined additional nucleotides are inserted at junctions during somatic recombination separate B cells have the same rearranged heavy chains with different rearranged light chains
67
allelic exclusion
only 1 allele for each is rearranged and expressed in a single B cell
68
allelic exclusion ensures that each B cell produces
antibody of a single antigen specificity
69
allelic exclusion allows for
clonal selection against only 1 pathogen
70
things that happen after antigen binding
surface Ig vs Secreted Ab somatic hypermutation isotope switching
71
first form of Ig is
membrane bound
72
membrane bound Ig
transmits signal of antigen binding to Ig into cell interior with the help of Iga and Igb coreceptors
73
after antigen binding, Ig is
secreted as antibody (plasma B cell)
74
somatic hypermutation
random introduction of single nucleotide mutations through entire rearranged V region DNA
75
somatic hypermutation is performed by the enzyme
AID (activation induced cytidine deaminase)
76
AID causes a __________ and is made only by _____________
point mutation proliferating B cells
77
result of somatic hypermutation
B cells with mutant surface Ig
78
somatic hypermutation leads to
selection of antibodies with higher affinity for infection pathogen
79
isotope switching
splice out C region of previous isotope
80
what antibody is made in the primary immune response?
IgM
81
why does the isotope need to switch from IgM?
so the antibodies can eliminate the pathogen properly
82
isotope switching depends on the
AID enzyme
83
switch region
highly repetitive DNA facilitates recombination
84
switching can occur
from m to any other isotype or sequentially
85
Hyper IgM immunodeficiency
no somatic hypermutation/class switching only low affinity IgM in large amounts
86
antibody effector functions
neutralization cells opsonization complement activation recruiting NK cells to kill sensitization of mast cells
87
what determines antibody effector functions?
isotype!
88
IgM
pentameric low affinity, high avidity
89
avidity
overall strength of multiple binding sites
90
IgG
smaller, more flexible transferred across placenta during pregnancy
91
IgA
secreted as monomer in blood, dimer in mucosal surfaces in lymphoid tissue under mucosa in lumen of gut and in milk, saliva, sweat, tears
92
what is the most abundantly produced Ig?
IgA
93
IgE
binds to mast cells, eosinophils, basophils eradicates parasites/response to allergen
94
IgG antibody has the most _______ functions why?
diverse hinge, elbow and tail regions give IgG flexibility
95
IgG has ______ different subclasses and they differ in _________________
four (G1-G4) structure of the hinge
96
IgG4 can exchange
1 heavy and light chain in circulation (functionally monovalent)
97
because IgG4 is functionally monovalent, it
can reduce immune response is elevated in allergic individuals

Immunology and Microbiology (22 decks)

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