Adaptive Immunity, B and T structure, receptors, and antibody

Question 1

what is the difference between B and T cell receptors?

Answer 1

B: contains antibody of defined specificity
T: specific for peptides derived from APC degraded antigen presented on MHC molecules

Question 2

what is the structure of a B cell receptor?

Answer 2

antigen binding specificity expressed with co-receptor involved in signa transduction
2 identical heavy chain
2 identical light chain

Question 3

when is B cell activated?

Answer 3

when antigens bind
(antigen can bind to one or two b cells which connects them)

Question 4

what are the coreceptor molecules for B cell receptor?

Answer 4

Iga (alpha), igb (beta)

transduce signals via ITAMS

Question 5

antibody has two forms:

Answer 5

membrane bound form and secreted Ig form

Question 6

what is the membrane bound form of antibodies?

Answer 6

serves as a signal receptor on B lymphocytes

Question 7

what is the secreted Ig form on antobodies?

Answer 7

do not have cytosolic segment, instead hydrophobic segment

Question 8

where are antibodies made?

Answer 8

B lymphocytes or plasma cells (highly differentiated B lymph that are specialized in secretion of antibodies)

Question 9

most antibodies are: (structure)

Answer 9

divalent
two symmetrical binding sites to allow cross linking

Question 10

what is special about the hinge region of the antibody?

Answer 10

proline rich area that allows extension

Question 11

what bond hods antibody structure together

Answer 11

disulfide
(has domains that are aso hed together by disulfide bonds)

Question 12

what possibilities make up the light chain?

Answer 12

kappa or lambda

Question 13

what possibilities make up the heavy chain?

Answer 13

Mu
gamma
alpha
delta
Epsilon

Question 14

how are immunoglobulins categorized?

Answer 14

which heavy chain is used

Question 15

what are the domains of an antibodies?

Answer 15

–variable light and heavy
–constant light
–CH1,2,3

Question 16

what is in the N terminal of amino acids?

Answer 16

antigen binding sites (Fab)

Question 17

what is at the C termina of antibodies?

Answer 17

Fc, crystallization (mediates effector activities)

Question 18

antigen bind to ______ derived by _______

Answer 18

antigen bind to the Fab fragment derived by the papain digestion from an antibody
(bind to determent from variable light and heavy chain)

Question 19

describe antigen antibody binding

Answer 19

one end of the Fab fragment (paratope) directly interacts with HA’s surface burying several amino acid residues. together these amino acids define the epitope

Question 20

what is a hypervariable region?

Answer 20

within the variable region, these AA make the closest contact with antigen at antigen binding sites
-these AA give the antibody its specify

Question 21

what is another name for hypervariable region?

Answer 21

complementary-determining regions, CDRs (1,2 or 3)

Question 22

what bonds form between antigen/antibody?

Answer 22

non-covalent
(van der waal, electrostatic, hydrogen, hydrophobic)

Question 23

describe the fit of antigen/antibody bonds?

Answer 23

require a close stearic fit
closer the fit the higher the affinity (binding specificity)

Question 24

what is antibody affinity?

Answer 24

strength of bond between singe antigenic determinant and singe combining site on antibody (may be mutivalent)

Question 25

what is the difference between affinity and avidity?

Answer 25

affinity is strength of individual bond avidity is strength of multiple bonds

Question 26

what are t cell receptors structurally similar to?

Answer 26

immunoglobulin domains

Question 27

what is the structure of a T cell receptor?

Answer 27

α and β, each has Variable and Constant regions Variable regions have three CDRs forming the peptide-specific binding site Constant regions each contain transmembrane regions

Question 28

TCR αβ recognizes and binds:

Answer 28

both antigen-derived peptide and MHC to which peptide is bound

Question 29

what are some co-receptors on T cells?

Answer 29

– CD3 contains ITAMs that transmit signals to the cell – CD4 and CD8 function in increasing the avidity of peptide binding by TCR – CD28 engages CD80 or CD86 on APC to fully activate a naive T cell

Question 30

what is phosphorylated on ITAMs?

Answer 30

CD3 (T cells) and Igα/β (B cells)

Question 31

Phosphorylated tyrosines serve as docking points for

Answer 31

adapter molecules

Question 32

what is clonal selection?

Answer 32

* When the B/T cell receptors engage with that antigen, the B/T cell becomes activated (also called “selected”) * Activation results in proliferation, producing a large number of clones

Question 33

what are the 5 types of immunoglobulins?

Answer 33

IgM IgA IgE IgG IgD (good chart on 111)

Question 34

What is the shape of IgG?

Answer 34

monomer

Question 35

where is IgG found?

Answer 35

blood steam and tissue fluid

Question 36

what is special about IgG?

Answer 36

it can cross placenta (not IgG2)

Question 37

what are the actions of IgG?

Answer 37

agglutinates * precipitates * opsonizes * mediates ADCC * activates complement * neutralizes

Question 38

what is opsonization?

Answer 38

IgG anchors bacteria to phagocytes for easier digestion

Question 39

what is antibody dependent ceII mediated cytotocity?

Answer 39

IgG anchors bacteria for NK ceIIs

Question 40

what is the shape of IgM?

Answer 40

pentamer

Question 41

what is special about the composition of IgM? (2 things)

Answer 41

has J chain that connects its parts H chain had extra domain (CH4)

Question 42

where is the membrane form of IgM expressed?

Answer 42

monomer version expressed on the ceII surface of early B ceIIs to serv ad BCR

Question 43

what are the jobs of IgM

Answer 43

* Agglutinates (has 5 binding sites) * Activates complement. * First immunoglobulin produced in an immune response * First immunoglobulin produced in infants * Provide early protection * Produced in response to T-independent antigens * Most efficient antibody for agglutination precipitation and complement fixation * Low affinity * Poor neutralization

Question 44

What is special about IgD?

Answer 44

not secreted, surface bound to mature B cells

Question 45

what does IgD do?

Answer 45

signal receptor triggers further differentiation of B lymphocyte

Question 46

where are IgA found?

Answer 46

externa secretions, colostrum, mil, saliva, mucus, sweat, tears

Question 47

what does IgA do?

Answer 47

agglutinates neutralizes

Question 48

which immunoglobulins have extra domains?

Answer 48

E & M

Question 49

what is IgE associated with?

Answer 49

allergies and sensitivities

Question 50

what occurs during the antigen independent stage?

Answer 50

generation of vast repertoire of B/T cells with out antigen telling specifics

Question 51

Diversity within the antibody repertoire is achieved by:

Answer 51

1. Selection of many mini-gene segments 2. Recombination to join the randomly selected mini- gene segments 3. Addition & deletion of nucleotides during joining of mini-gene segments 4. Association of different light and heavy chains to form binding sites

Question 52

END OF THIS ECTURE WHATIS IT??