C3.2 - adaptive immunity (3q)

Question 1

what are lymphocytes?

Answer 1

white blood cells that circulate in the blood and are contained in lymph nodes
- an individual has a very large number of T and B-lymphocytes that each make a specific type of antibody, which binds to a specific antigen

Question 2

what is the role of lymphocytes in adaptive immunity?

Answer 2

lymphocytes are a range of cells that cooperate to produce antibodies which provide adaptive immunity

Question 3

what is the role of antigens?

Answer 3

antigens are recognition molecules that trigger antibody production, and each pathogen has a specific antigen, that allows the pathogen to be recognised through cell receptors binding to the antigen

Question 4

what type of molecules are antigens?

Answer 4

antigens are usually glycoproteins or any other protein

Question 5

where are antigens usually located within pathogens?

Answer 5

antigens are usually located on the outer surface of pathogens

Question 6

what is an outline of antibody production?

Answer 6

1. antigen presentation by macrophages
2. clonal selection of helper T-cells
3. clonal selection of B-cells
4. Clonal expansion of B-cells
5. Differentiation to plasma and memory cells

Question 7

what is the full process of antibody production?

Answer 7

1. macrophages engulf the pathogen, digest it and present its antigens
2. helper T cells are activated by binding to a specific antigen
3. activated helper T cells activate the corresponding B cells only if it is directly binding to the antigen
4. activated B cells repeatedly divide by mitosis to produce large numbers of clones
5. B cells differentiate to form:
   - memory cells that provide immunity
   - plasma B-cells that produce and secrete the same antibody, which is specific to the presented antigen, destroying the pathogen
6. antibody production lasts for several days until all the antigens are destroyed

Question 8

why is antigen presentation necessary?

Answer 8

allows the innate immune system to trigger an adaptive immune system response

Question 9

why is clonal selection necessary?

Answer 9

to identify which T and B-lymphocytes are able to cause the production of antibodies that will bind to the specific antigen

Question 10

why is clonal expansion necessary?

Answer 10

• there are a small numbers of B-cells that respond to a specific antigen
• clonal expansion allows sufficient quantities of antibody to be produced, to destroy the pathogen

Question 11

why is differentiation necessary?

Answer 11

• produces some plasma cells that produce antibodies to destroy the pathogen in the current infection
• produces some memory cells that provide long-term immunity

Question 12

what is immunity?

Answer 12

immunity is the ability to eliminate an infectious disease from the body, destroying the pathogen before it causes any symptoms

Question 13

what causes immunity?

Answer 13

• immunity is a consequence of retaining memory cells
• some memory cells survive for a lifetime, however, many gradually decline unless a person is repeatedly infected with the corresponding pathogen

Question 14

what is the difference between the antibody production in the primary and secondary immune response?

Answer 14

• faster = no clonal selection needs to occur as there is a large number of memory cells that can produce the antibody quicker
• more antibodies = memory cells rapidly reproduce to from plasma cells

Question 15

in what context would a second infection by the same pathogen cause a primary response?

Answer 15

if mutation had changed the antigen structure, so the memory cells won’t bind to the pathogen and produce antibodies quickly and at a high concentration