Plasma cells secrete antibodies against specific antigens. Outline how plasma cells become activated.

A hybridoma is a cell produced by the fusion of a plasma cell with a tumour cell. Explain the advantages of using hybridoma cells in the production of monoclonal antibodies.

State one use of monoclonal antibodies.

a. macrophages/phagocytes recognize/engulf pathogen and display antigens ✔

b. antigen binds to T cell/helper T cell / antigen causes activation of T cell ✔

c. antigen binds to antibodies in membrane of B cells ✔

d. (activated) T cells activate B cells (that have the antigen bound to them) ✔

e. activated B cells divide to produce a clone of cells ✔

f. active plasma cells develop from the clone of cells/from activated B cells ✔

Accept B-lymphocyte and Tlymphocyte instead of B cell and T cell throughout the answer.

a. endless cell divisions/unregulated mitosis (in hybridoma cells) ✔

b. large clone/population of identical cells produced ✔

c. all cells (in clone) produce same type of antibody ✔

d. large amount of (chosen) antibody can be produced ✔

For mpa it must be clear that it is the hybridoma cells not tumour cells that divide endlessly and that division is more than just rapid.

a. pregnancy testing kits/detection of hCG (to diagnose pregnancy) ✔

b. produce antibodies for treating arthritis/C.difficile/anthrax/psoriasis/ulcerative colitis/asthma/ankylosing spondylitis/Crohn’s disease/multiple sclerosis/HIV/other named disease if verified / targeting tumor cells in treatment of cancer
OR
gives artificial/passive immunity (if injected) ✔

c. blood typing/testing urine for drugs/other verified specific use of monoclonal antibodies ✔

Mark only the first answer.

Some explanations of the production of active plasma cells were excellent but weaker candidates were mostly very confused, with antigens and antibodies muddled up. Many candidates thought that plasma cells are already present and just need to be activated, rather than them being produced as a result of the activity of macrophages, T-cells and B-cells. There was too much focus on memory cells. The mean mark was low, 0.6 out of 3.

This was another low-scoring question for most candidates. Many did not understand well enough how hybridoma cells are produced. There was also a lack of distinction between rapid proliferation of cells and proliferation that continues indefinitely.