59-Antibody Structure and Function Flashcards Preview

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Flashcards in 59-Antibody Structure and Function Deck (48)
1

antigen receptors

on surface of lymphocytes
B cell receptors
T cell receptors
many different receptors to recognize unlimited number of foreign Ags
clonically expressed-1 unique Ag receptor per lymphocyte clone

2

Surface BCR and soluble Ab molecules

identical except small transmembrane sequence on C terminal end

3

function of BCR

recognition of antigen
initiates signal transduction using CD79a/b to start intracellular signaling

4

CD79

needed for BCR to start intracellular signalling

5

structure of Ab

2 heavy chains
2 light chains
hinge region for torsion
disulfide bonds to hold molecules together
N linked carb chains linked to heavy chain for 3D structure and half life

6

variable region

heavy-VDJ
light-VJ
form antigen binding pocket, 2 identical pockets that bind identical antigens

7

constant region

no recombination, ensure structural integrity
H chain is for key effector functions

8

Fab region

Ag binding, 2 Fab regions=Fab2, bind 2 identical antigens

9

Fc region

below hinge region, heavy chain constant region
effector functions

10

Fab

cleave above hinge

11

Fc

cleave above hinge

12

Fab2

cleave below hinge

13

hypervariability regions

3 regions in both heavy and light, "complementarity determining regions"
1 and 2 and encoded in DNA
3 is recombination of VDJ or VJ

14

CDR

complementarity determining regions, variability in heavy and light chains
proximal in tertiary structure and form Ag binding pocket

15

epitope

small segment of Ag bound by Ag binding pocket, non covalent interactions

16

what can TCRs recognize vs BCR/Ag

TCR-peptides, require MHC
BCR/Ag-lipid, carb, protein, nucleic acid, interact with epitopes on surface of pathogens, do not require MHC

17

end product of B cell activation

cell that secretes Abs (soluble version of BCR) that recognize pathogen epitope and bind then recruite innate immunity to mediate destruction

18

Ab isotypes

defined by heavy chain constant region
5 isotopes encoded by loci
IgM, G, A, E, D

19

subclasses of Ab

IgG-4
IgA-2

20

IgM structure

4 constant regions, no hinge
large and inflexible=only in blood
secreted as pentamer-10 binding sites

21

antibody that is a pentamer

IgM

22

IgM functions

neutralization
agglutination
complement activation

23

neutralization Abs

IgM, IgG, IgA

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agglutination Abs

IgM, IgG, IgA

25

complement activation Abs

IgM, IgG

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IgG structure

3 constant regions with hinge
secreted as monomer-2 binding sites
most abundant
found in blood and tissues

27

antibody that is a monomer

IgG, IgA in blood, IgE

28

IgG functions

neutralization
agglutiniation
complement activation
opsonization/phagocytosis
Ab dependent cellular cytotoxicity
transplacental transfer

29

opsonization/phagocytosis Abs

IgG, IgA

30

Ab dependent cellular cytotoxicity Abs

IgG

31

passive immunity to fetus through placenta Abs

IgG

32

IgA structure

3 constant regions with hinge
monomer in blood
dimer in mucosal secretions

33

antibody that is a dimer

IgA in mucosal secretions

34

IgA functions

neutralization
agglutination
opsonization/phagocytosis
immunity in breast milk

35

immunity in breast milk Abs

IgA

36

IgE structure

4 constant regions, no hinge region
monomer

37

IgE function

bound to mast cells with high affinity
mediate type 1 hypersensitivity reaction/ allergic reaction

38

allergic reaction Abs

IgE

39

IgD structure

3 constant regions with hinge, rarely secretes, used as BCR on naive B cells

40

no hinge

IgM, IgE

41

agglutination

traps microbes in a complex
impair movement, attachment, replication, colony formation
IgM, G, A- lots of binding sites or hinge with torsion

42

neutralization

prevent pathogens and toxins from binding to their host
IgM, G, A

43

Complement activation-Classical pathway

Ab binding to Ag makes immune complex formation
allosteric change in Fc to bind C1q to start complement cascade, Use IgM, G

recruit C4 and 2, activation of C3 convertase
cleave C3, C3a inflammation, C3b opsinization
recruit and cleave C5, C5a inflammation
C5b recruits C6, 7, 8, 9 to form MAC, create channel and lyse

44

Opsonization

coating of pathogen with ligand recognized by phagocytic cells
IgG, IgA, C3b

45

Phagocytic cell receptors

Fc receptor bind antibodies
C3b receptor bind C3b
4 IgG Fc receptors, 1 IgA Fc receptor, 4 C3b receptor

46

natural killer cells

IgG Fc receptors bind IgG Abs with their Fc tail
provide specifficity to NK cells to recognize and bind Ags on target cells
kill using proteolytic enzymes and inducing apoptosis

47

maternal IgG

to fetus through circulation
can cause disease
hemolytic disease of newborns
IgG aBs against Rh blood group, give RhoGAM to Rh- moms

48

maternal IgA

in mothers milk
protect baby's gut