White blood cells & the immune systemWhat does it mean to be immune to something?

Leucocyte (WBC)

Phagocytes (engulf & destroy) = Inflammation

Lymphocytes (B cells & T cells)

B-lymphocytes secrete antibodies into the blood stream

Bacterial antigens – end up on the surface of the phagocytes that have destroyed them

These are then called ‘antigen presenting cells’ or APC

Antibody structureAntibody = a protein called an

immunoglobulin (Ig)

8C Immunity

Immunity – memory cells remain in the body following previous exposure to an antigen

The immune response

1.20 Describe Edward Jenner’s contribution to the development ofvaccines1.21 Explain the process of immunisation, including:a harmless pathogen or antigenic material introducedb the antigens trigger an immune response which causes theproduction of antibodiesc the antigens also trigger production of memory lymphocytes1.22 Demonstrate an understanding of the advantages and risksassociated with immunisation1.23 Describe the role of memory lymphocytes in secondaryresponses to antigen; interpret data showing variation inblood antibody levels in response to first and subsequentinfections

1.24 Describe the production of monoclonal antibodies,including:a use of B lymphocytes which produce desired antibodies but do not divideb production of hybridoma cellsc hybridoma cells produce antibodies and they divide

Monoclonal antibodies

Making monoclonal antibodies

1.25 Use of monoclonal antibodies:a pregnancy testingb diagnosis - locating blood clots and cancer cells

treatment - cancerc advantages of using monoclonal antibodies totarget specific cells (compared to drug and radiotherapy treatments)

Monoclonal antibodies to hCG are used in pregnancy tests

Highly specific = no false positivesVery sensitive = can be used early in pregnancy when hCG levels are low (first day of missed period)Cheap & easy to produce – cell biology & tissue culture of hybridoma cells

Monoclonal antibodies as an anti-cancer therapy

£39,000 for one individual to receive a twelve month course of treatment.

Herceptin: a new cancer treatment

How does Herceptin® work?• It is an antibody that binds to a receptor that is over-

expressed in breast cancer cells, in 25-30% of patients(the HER2 receptor for human epidermal growth factor)

• Patients with this characteristic (late stage metastatic breast cancer) tend to respond poorly to conventional chemotherapy (cytotoxic drugs) or hormonal therapy (anti-oestrogen)

• By binding to the receptors, the drug can ‘switch off’ the signal that tells the cells to keep dividing

• Approximately 175,000 women develop breast cancer every year in Europe.

• 20% of all deaths in women are caused by breast cancer (1:5)