B cells: antibodies

Question 1

Structure of ab = shape

Answer 1

Y shaped glycoprotein
- contains carb covalently linked to protein

Question 2

Ab aka

Answer 2

Immunoglobulin (ig)

Question 3

Describe immunoglobulin

Answer 3

Protein fam to which abs and B cell receptors belong - these are ig like domains

Question 4

What are abs made up of

Answer 4

2 identical disulfide linked heavy chains and 2 identical light chains
4 chains in total

Question 5

Describe variable region

Answer 5

Both heavy and light chain have a variable region

Question 6

Describe constant region

Answer 6

Both heavy and light chain have a constant region

Question 7

Name all regions of ab

Answer 7

Vl = variable region in lc
Vh = variable region in hc
Cl = constant region in lc
Ch = constant region in hc

Question 8

Variable region functions

Answer 8

Ag binding
Vl and vh = forms antigen binding site= 2 identical sites per ab
Binding can result in neutralization and other fucntions

Question 9

Constant region functions

Answer 9

Involved in complement activation - c1q—> classical pathway
= binding ag —> cascade classical pathway
Constant region fc binding fc receptors

Question 10

What else can constant region do - explain more

Answer 10

Constant region fc binding fc receptors On phagocytes and other cell types like mast cells, eosinophils
= fc receptors Bind fc region = can lead to phagocytosis, or secretion of histamine/granulocytes

Question 11

Describe fab fragments

Answer 11

2 fab fragments per ab
Each has ag binding domain and part of Constant heavy and light chains

Question 12

Describe fc fragment

Answer 12

One fragment
Constant region heavy chain
Receptors that bind abs recognize fc portion

Question 13

Fab =

Answer 13

Fragment antigen binding

Question 14

Fc =

Answer 14

Fragment crystallizable

Question 15

Describe 3d structure ab - bonds/what’s it look like

Answer 15

Held together by inter/intra chain disulfide covalent bonds - keeps everything together
Both constant and variable regions folded in complex 3d structure including beta strands

Question 16

Describe variable region - complementarity determining region

Answer 16

Cdr = ag binding site, has direct contact with ag
Hyper variable loops -3per variable do domain (2hc/lc = 6x2 cdrs = 12 cdrs per ab)
Not part of beta stands

Question 17

What do cdrs have

Answer 17

Greatest variability in ab sequence = highly variable

Question 18

Where are cdrs

Answer 18

At extremities of ab
At ends of abs = direct binds ag

Question 19

Describe ag binding to ig

Answer 19

Ag binding to ab = involves non covalent bonding between ig and ag epitope
Uses other types of interactions

Question 20

What types of interactions involved when. Ag binds ig - name some

Answer 20

Hydrogen bonds
Van der waals
Hydrophobic ionic

Question 21

Describe antibody:antigen binding - specificity

Answer 21

Lock and key specificity

Question 22

Describe antibody:antigen binding - Where is it

Answer 22

Extremities of abs

Question 23

Describe antibody:antigen binding - Is there a size restriction for ag

Answer 23

Size variability of what’s being recognized by ab

Question 24

Describe antibody:antigen binding - Are cdrs the same length

Answer 24

Variantion in ab = cdrs vary in length

Question 25

Describe antibody:antigen binding - Location of epitopes

Answer 25

Can be anywhere on ag

Question 26

Antibody classes

Answer 26

5 major classes Diff number of ig like domain, diff lengths of constant region of heavy chain Diff carb groups

Question 27

What differentiates the 5 major classes of abs

Answer 27

By aa sequence of heavy chain constant region = heavy chain differentiates diff abs Fc fragment of each ig = diff

Question 28

Do all antibody classes do same things

Answer 28

Noooo Each class does diff fucntions during immune response

Question 29

Describe igm structure

Answer 29

Pentameric - 5 igms linked 5 abs linked together via disulphide bonds Heavy chain = one variable region and 4 constant regions

Question 30

Describe igm - expressed on

Answer 30

Mature naive B cells express transmembrane igm prior to activation

Question 31

Describe igm functions

Answer 31

Part of first wave of secreted abs - plasma blasts Most effect initiator of complement cascade

Question 32

Why is igm good at initiating complement

Answer 32

Binds c1q = makes good landing pad bc of igm size

Question 33

Describe igd structure

Answer 33

Heavy chain = one variable region and 3 constant regions - so shorter

Question 34

Describe igd functions

Answer 34

Part of first wave of secreted abs = some secreted only

Question 35

Describe igg structure

Answer 35

Heavy chain = one variable region and 3 constant regions

Question 36

Describe igg fucntion

Answer 36

Most abundant in plasma 2 subclasses in humans = igg1,2,3,4 Produced following differentiation in germinal centre = bc class switching only happens here

Question 37

Describe ige structure

Answer 37

Heavy chain = one variable region and 4 constant regions

Question 38

Describe ige fucntion

Answer 38

Produced in response to helminth infection - th2 response

Question 39

Describe iga structure

Answer 39

Heavy chain = one variable region and 3 constant regions Monomer in plasma Dimmer in mucous secretions through j chain (majority, j chain = polypeptide linking disulfide bonds)

Question 40

Describe iga functions

Answer 40

Important for mucosal immunity 2 subclasses = iga1, iga2

Question 41

Describe experimental and clinical uses of abs - what can abs be made to bind

Answer 41

Can be made to bind virtually any epitope Can be made to bind another ab

Question 42

Describe experimental and clinical uses of abs - ex of ab binding any epitope

Answer 42

antibody against TNF- for the treatment of rheumatoid arthritis

Question 43

Describe experimental and clinical uses of abs - ex of ab binding to another ab

Answer 43

an antibody against the Fc region of IgG

Question 44

Describe Elisa

Answer 44

Enzyme linked immunosorbent assay = if want to know how much of a protein in sample Primary ab specific to target and secondary ab specific to fc region primary ab and conjugated with colour More intense the colour = means more fo protein fo interest

Question 45

Describe western blot

Answer 45

Intensity of band = how much Size = see if bound to something 2nd and conjugated so can see band

Question 46

Describe immunogenicity - note

Answer 46

Possible for immune system to mount an immune system response against therapeutic drug - including mabs Slowly mimic human ab and decrease immunogenicity of it - to make as similar to human ag but prevent immune response