B cell activation, hypermutation and class switching

Question 1

in the bone marrow

Answer 1

progenitor B cells produce a precursor B cell by somatic mutation of the heavy chain

Question 2

precursor B cell produces

Answer 2

an immature B cell via somatic mutation of light chain (IgM)

Question 3

immature B cell (IgM) migrates to the

Answer 3

lymph nodes via efferent lymphatic system

Question 4

in the lymph nodes B cells producing

Answer 4

become maturee in the lymph nodes, expressing IgM and IgD

Question 5

B cell activated by

Answer 5

T helper cell or antigen of a pathogen or dendritic cell

Question 6

after B cell activation by T helper cell or antigen

Answer 6

B cell moves into the germinal centre and begin to proliferate via clonal expansion

Question 7

what introduces point mutations into variable regions of the DNA that code for variable antibody

Answer 7

AID

Question 8

AID is an

Answer 8

intracellular enzyme which introduces point mutations in the variable regions of DNA that codes for variable regions of the antibody—> introducing mutations (hypermutation)

Question 9

hypermutation to the DNA encoding variable regions of the antibody causes

Answer 9

either an increase or decrease in antibody affinity to specific antigen

Question 10

hypermutation produces

Answer 10

many types of B cells which produce antibodies with either ran increased affinity or decreased affinity for antigen

Question 11

B cells then present their antibodies to

Answer 11

T helper cells which still carries the antigen originally presented to the B cell

Question 12

B cells with disadvantageous mutations

Answer 12

have a lower affinity for antigen…. are destroyed via apoptosis

Question 13

B cells with mutation which have increased affinity of antibody undego

Answer 13

class switching and differentiation

Question 14

B cells with increased affinity undergo differentiation into

Answer 14

plasma cells or memory B cells

Question 15

hypermutation via point mutations (AID) leads to

Answer 15

changes in variable regions –> changes to CDRs… leading to increased or decreased affinity

Question 16

decreased affinity

Answer 16

apoptosis

Question 17

increased affinity

Answer 17

proliferation stimulation… class switching via isotope switching

Question 18

order of B cell activation

Answer 18

BONE MARROW

1) progenitor B cell produced in Bone marrow by somatic mutation of heavy chain
2) Precursor B cell produces an immature B cell via somatic mutation of light chain

MIGRATION TO LYMPH NODES

1) presented to T- helper cell, dendritic cell or antigen
2) becomes mature

MOVES TO GERMINAL CENTRE

1) point mutations by AID increasing and decreasing affinity for antigen
2) present antibodies to T helper cell again
3) those with high affinity proliferate, those will low apoptose