Haemophilia B is a rare genetic disorder where the body produces very little or no factor IX, a protein that is responsible for a cascade of reactions resulting in the conversion of fibrinogen into fibrin.
Explain the effect of insufficient levels of factor IX on the process of blood clotting.
Haemophilia B cannot be cured but one form of treatment involves injecting patients with factor IX, which is derived either from donated blood or artificially produced using genetic engineering.
Explain the importance of determining the correct dosage of factor IX before injecting patients.
Lupus is an autoimmune disease in which the immune system will produce autoantibodies against the body's own tissue. This results in a variety of symptoms, including inflammation of the skin and organs to more serious ones such as organ failure and strokes.
Compare and contrast an autoimmune response to the immune response against a pathogen.
There are a variety of ways to treat lupus. One form of treatment involves administering immunosuppressive drugs which prevents the activation of lymphocytes.
Explain the impact that this form of treatment could have on a lupus patient.
T-cells are another type of white blood cell that can help the body fight against infections. Instead of producing antibodies, T-cells will bind to the surface of infected or defective cells and destroy them directly. This ability has been harnessed in a new type of cancer treatment known as chimeric antigen receptor (CAR) T cell therapy.
During CAR T cell therapy, normal T cells from the patients blood are modified to enable them to bind to cancer cells with the help of cell surface receptors. The following diagram shows the treatment process of CAR T cell therapy.
Contrast the differences between a normal T cell (stage 1 of the diagram) and a CAR T cell (stage 3 of the diagram).
Traditional forms of cancer treatment include chemotherapy during which toxic chemicals are inserted into the blood stream of a patient. These chemicals will circulate through the body and kill any fast-dividing cells, which often leads to uncomfortable side effects such as hair loss, nausea and skin rashes. The chemicals used during chemotherapy are broken down by the body and therefore have a short-lived effect, requiring patients to receive multiple treatments on a regular basis in order to be effective.
Based on the information provided and your knowledge of the immune system, suggest two advantages of CAR T cell therapy over chemotherapy.
B lymphocytes are a type of white blood cell. These lymphocytes produce antibodies in response to activation by the presence of an antigen on a pathogen.
The diagram below shows the appearance of a B lymphocyte before and after it has been activated.
Explain the changes that can be observed within the B lymphocyte when it is activated.
Rituximab is a type of antibody that is used to treat certain B lymphocyte cancers (leukaemia). It binds to the cell surface protein CD20 found on B-lymphocytes. Once the antibody binds to the protein it triggers cell death in the cancerous B-lymphocyte. Patients are given rituximab through a drip into a vein on a regular basis for the duration of their cancer treatment.
Based on your knowledge of the immune system, explain why patients would need regular infusions with rituximab.
When treating more aggressive forms of B lymphocyte cancer, rituximab is often combined with more traditional chemotherapies.
The graph below shows the results of a trial looking at the effects of several different treatments, alone and in combination, on B lymphocytes grown in the laboratory.
Rituximab on its own killed 23% of the B lymphocytes while when combined with hydroxyurea it killed 82% of B-lymphocytes in the laboratory.
Calculate the percentage effectiveness of using rituximab in combination with hydroxyurea compared to rituximab on its own. Show your working and give your answer to three significant figures.
