B cells and antibodies Block A

Question 1

what does the adaptive immune response provide ?

Answer 1

specificity and diversity to make sure that the immune response is targeted to a specific and relevant microbe. It can respond to a large variety of microbes .

Question 2

does the adaptive provide memory cells and why ?

Answer 2

It produces memory cells so that it has an increased ability to combat infection from the same microbe , this is how vaccines work

Question 3

what allows the response to reset and why?

Answer 3

contraction and homeostasis so that there isn’t an excessive inflammation and bystander damage and also autoimmune disease.

Question 4

what prevents an autoimmune disease ?

Answer 4

non reactivity to self antigens and commensal antigens

Question 5

the B and T cells are key , what needs to occur and why with them ?

Answer 5

they need to be in contact by binding through receptors so that communication can occur

Question 6

what are antibodies also called ?

Answer 6

immunoglobins , Ig

Question 7

what are antibodies composed of ?

Answer 7

2 identical heavy chains , 2 identical light chains that re held together by disulfide bridges.

Question 8

whats the 2 regions on an antibody ?

Answer 8

variable region - where binding to the antigen epitope occurs
constant region called the C terminus

Question 9

what is the binding site of the antigen ?

Answer 9

epitope

Question 10

does a single antigen have one or more epitopes ?

Answer 10

can have many

Question 11

when are B cells generated ?

Answer 11

in the bone marrow

Question 12

what do B cells express that recognise an antigen ?

Answer 12

BCR , B cell receptor

Question 13

are all the BCR’s the same ?

Answer 13

no and this is what generated diversity to the adaptive immune response.

Question 14

what makes the receptors on each lymphocyte differ ?

Answer 14

the recombination of gene segments

Question 15

what’s BCR structure of the B cells ?

Answer 15

surface bound antibodies of the same specificity.

Question 16

when does a b cell mature ?

Answer 16

when it expresses the functional BCR it matures from the bone marrow to enter the periphery where it migrates via the lymph nodes

Question 17

stages of B cell activation ?

Answer 17

• Recognition of antigen by BCR leads to activation of B cell and internalisation of antigen
• Once internalised, antigen is broken down into peptides
• Peptides are loaded into MHC-II within the B cell and presented to antigen-specific CD4+ T cells – helper T cells
• If T cell also recognises antigen, provides ‘help’ to B cell (cytokines, costimulation)
• Allows B cell to fully activate into plasma cell and secrete antibodies.

Question 18

what are C40L and CD40 ?

Answer 18

co stimulating factors for T cell

Question 19

what occurs if a cell lacks the co stimulating factors ?

Answer 19

there is no cognate interaction between the B and T cell and there is no activation of the B cell so no antibodies are produced

Question 20

what are Cd4+ ?

Answer 20

helper T cell surface proteins , MHC class II

Question 21

how do CD4+ helper cells asisst ?

Answer 21

• Recognise the antigen
• Co stimulate
• Cytokine

Question 22

what does the secretion of cytokines cause ?

Answer 22

• Induces proliferation of B cell and differentiation
• Plasma cell (antibody-secreting)
• Memory cell which are specific to antibody.

Question 23

what’s the 3 functions of an antibody?

Answer 23

neutralisation
opsinisation
complement

Question 24

neutralisation ?

Answer 24

a mechanism in which the antibody produced from the B cells will bind to the antigens on the viruses surface which results in it no longer being able to bind to the host cell and can therefore no longer take over the host cell to cause further damage. This is also done for viruses and their viral toxins.

Question 25

opsinisation ?

Answer 25

involves the antibodies binding to the antigens on the viruses surface , however it does not block the viruses from binding to the host cell , instead it labels the pathogen so it Is recognised by a phagocytic cell so that the pathogen can be degraded using phagocytosis.

Question 26

complement ?

Answer 26

the antibodies work together with the proteins involved in the complement system. When they bind together and bind onto a foreign cell this causes the membrane of the pathogen cell to swell up and burst