Monoclonal antibodies are pure, single substances produced in the laboratory, each from a single clone of lymphocytes. Students need not know any detail of their production but may appreciate that they result from the fusion of single lymphocytes with tumour cells which have been made harmless. The use of tumour hybrid cells the ability to divide continuously (normal lymphocytes cannot do large quantities of monoclonal antibodies are made and released.
Monoclonal antibodies, because of their purity and high degree of specificity are finding increasing use in medicine and industry, as a means of targeting specific substances. One well known use is in pregnancy testing kits where a monoclonal antibody, specific for a hormone present in the urine of pregnant women, is used.
The aspect relevant to this syllabus section is the potential for targeting specific molecules in the body which are part of disease processes. In this way, sufferers from and carriers of specific diseases may be identified, and treatments devised.
In some cases, diseased cells have proteins on their surface which are different from, or additional to, those on healthy cells, enabling these abnormal cells to be targeted. In other cases, poisonous proteins themselves cause disease symptoms. One procedure involves making monoclonal antibodies to these proteins and joining the monoclonal antibody molecules to toxic drugs. The antibody, carrying its toxin tag, then homes in on the diseased cells only, or the dangerous proteins, destroying them. Tetanus toxin has already been destroyed using this procedure and there are hopes of destroying some types of tumour cells, using poisons such as ricin tagged to monoclonal antibodies.