Lectures 1&2 - Immunology overview and polypeptide chains of antibodies

Question 1

which two cells is specific/acquired immunity mainly mediated by?

Answer 1

B and T cells

Question 2

what is secreted when a B cell is activated?

Answer 2

anitbodies

Question 3

what do the C regions of an antibody react with ?

Answer 3

complement /FC receptors

Question 4

what are the V regions of an antibody specific to?

Answer 4

an antigen

Question 5

which chain in an antibody determines the isotype?

Answer 5

heavy

Question 6

which chain of an antibody has 2 domains? what are they?

Answer 6

light chain has 2 domains

lamda and kappa

Question 7

what 4 types of antigens can antibodies recognise?

Answer 7

peptide, carbohydrate, lipid and nucleic acid

Question 8

how many hypervariable regions does an antibody have in total?

how many in each of the light and heavy chain?

Answer 8

6 in total

3 from light, 3 from heavy chain

Question 9

what does Fab stand for? (antibodies)

Answer 9

fragment antigen binding (variable region)

Question 10

what does Fc stand for? (antibodies)

Answer 10

fragment crystallisable (constant region)

Question 11

what type of family do antibodies, MHC molecules and T cell receptors belong to?

Answer 11

glycoprotein family

Question 12

T cells express a T cell receptor which recognizes the……… fragment of an antigen, bound to a ……. molecule

Answer 12

peptide fragment
MHC molecule

Question 13

class 1 MHC molecules are expressed on which cells?

Answer 13

all nucleated cells

Question 14

class 2 MHC molecules are expressed on which cells?

Answer 14

antigen presenting cells/APCs

Question 15

which 3 genes do class 1 MHC have?

Answer 15

HLA, HLB, HLC

Question 16

which 3 genes do class 2 MHC have?

Answer 16

HLA DP, HLA DQ, HLA DR

Question 17

which type of T cells do MHC class 1 recognise?

Answer 17

cytotoxic CD8+

Question 18

which type of T cells do MHC class 2 recognise?

Answer 18

CD4+

Question 19

in the H chain of antibodies and the TCR beta receptors, which 3 gene segments encode the V region?

Answer 19

V, D, J

Question 20

in the L chain of antibodies and the TCR alpha receptors, which 2 gene segments encode the V region?

Answer 20

V and J

Question 21

in H chain recombination which 3 gene segments are joined together?

Answer 21

V, D and J

Question 22

In H chain recombination what is the order of joining of the V, D and J segments? (2 steps)

Answer 22

1) D to J
2) V- DJ

Question 23

in L chain recombination, the V and J gene segments are joined. Does it happen in the kappa or lamda chain initially?

what happens if this chain is unsuccessful in recombination?

Answer 23

kappa

if unsuccessful, then lamda segments are recombined

Question 24

on which chromosomes are these chains found (antibodies)? :

• H chain
• Kappa light chain
• Lamda light chain

Answer 24

H chain on chromosome 14

kappa light chain on chromosome 2

lamda light chain on chromosome 22

Question 25

the heavy chain for an antibody is C-mew / Cu. What is its class/epitope?

Answer 25

IgM

Question 26

what do the recombination activating genes 1 and 2 (RAG-1,2) encode for, involved in Ig gene segment rearrangement)?

Answer 26

lymphoid specific components of VDJ recombinase

Question 27

what do mutations in RAG genes lead to?

Answer 27

immunodeficiency

Question 28

can B cells express both the kappa and lamda rearrangements?

Answer 28

no, either one or the other

Question 29

imprecise joining are differences in sequences where which two gene segments join?

Answer 29

V-D and D-J

Question 30

what are N regions, creating junctional diversity, a random addition of at V-D and D-J junctions?

Answer 30

nucleotides

Question 31

random nucleotide addition at V-D and D-J segments is done by which enzyme?

Answer 31

terminal transferase

Question 32

where does somatic hypermutation occur in antibodies?

Answer 32

germinal centres

Question 33

in which genes of antibodies is mutation frequency the highest?

Answer 33

VH/VL (V) genes

Question 34

what is the function of AID enzyme? (hint: deamination of one base to another) what does it lead to?

Answer 34

acts on DNA to deaminate cytosine to uracil mutations

Question 35

class switching of antibodies is done in which chain?

Answer 35

heavy

Question 36

why is IgM the first class of antibody to be expressed in a developing B cell at the heavy chain locus?

Answer 36

in the heavy chain locus, C-mew/Cu is the closest segment to the VDJ gene segments

Question 37

how many transmembrane domains do MHC class 1 and MHC class 2 molecules have respectively?

Answer 37

MHC 1 = 1 MHC 2 = 2

Question 38

which MHC molecule binds smaller amino acid chains? how long are the chains which each MHC class bind?

Answer 38

MHC 1 binds smaller - 8-10 AAs MHC 2 binds larger - 13+ AAs

Question 39

what does HLA stand for?

Answer 39

human leukocytic antigen

Question 40

true or false, TCRs can only recognise peptides as opposed to antibodies which can recognise peptides, carbs, lipids and NAs?

Answer 40

true, they can only recognise peptides

Question 41

which chain of MHC class 1 molecules doesn't bind to the associated peptide?

Answer 41

beta - 2 microglobulin it is the alpha chain which binds the peptide

Question 42

How are the heavy (H) chain of an antibody and the beta (b) chain of the TCR similar?

Answer 42

both only involve the V and J segments for recombination

Question 43

WHEN does rearrangement of Ig genes occur?

Answer 43

early stages of B cell development

Question 44

There are 5 distinct mechanisms that allow for antibody diversity; list them? which mechanism involves the addition of nucleotides by terminal transferase? which mechanism involves AID enzyme?

Answer 44

1) VDJ recombination 2) SHM (AID enzyme) 3) junctional diversity (nucleotides added by TT) 4) class switching 5) combinatorial diversity