1.5
Paul Ehrlich is the father of modern chemotherapy. His work 
has led to today's scientists being able to tailor-make drugs 
to kill particular bacteria. In his student days he used the 
synthetic aniline dyes to stain the blood cells and other body 
tissues. His finding that the dyes coloured the various parts 
of the cells in different ways laid the foundation for the 
science of haematology. Even more important, since aniline 
dyes were known to kill bacteria in the laboratory, the next 
step was to see whether they kill them in the body without 
harming it. He expressed himself thus: "Antitoxins and 
antibacterial substances are charmed bullets which strike 
into those objects for whose destruction they have been 
produced." He used variants of organic arsenicals to treat 
protozoal and spirochaetal infections in animals. At the age of 
55 his long search was rewarded by the discovery of 
salvarsan, or "606", which was effective in killing 
spirochaetes within tissues and which reigned supreme in 
the treatment of syphilis until the introduction of penicillin. 
And the use of specially designed 'magic bullets', as they are 
now usually termed, has become a standard technique in 
modern medicine
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2.3
A major advance in the fight against cancer may have been 
found after trials with a family of substances that should 
remove the rejection problem in tissue and organ transplants 
and transform the treatments for killing cancerous cells. The 
coming revolution depends on a new way of designing and 
mass-producing human antibodies, the natural agents in the 
blood that form the body's main weapons system to destroy 
poisons, ranging from snake venom to toxins, produced by 
infectious bacteria and viruses. Medical researchers have 
dubbed the method low-impact therapy.

The advance is due in large measure to the achievements of 
research groups at Cambridge: at the University School of 
Clinical Medicine, Addenbrooks Hospital, and the Medical 
Research Council's Laboratory of Molecular Biology and its 
adjoining Interdisciplinary Research Centre for Protein 
Engineering.

Their discoveries have spurred a multi-million pound, world-
wide offensive in research into the refinement of the most 
promising tools for treating human disease in the past 
decade. Yet the new methods, which employ the most 
exquisite applications of the scientists' new-found abilities in 
genetic engineering, represent a third generation of a medical 
technology that originated precisely 100 years ago.

The origins belong to the development of immunisation of 
children against diphtheria by 19th-century German 
bacteriologists Paul Ehrlich and Emil Behring, and a Japanese 
collaborator called Bron S.Kitasato. They showed that an 
animal inoculated with diphtheria toxin could produce a 
protective serum. Animal antisera were used for a variety of 
bacterial infections and neutralising toxins, which led to 
antibiotics and the start of the modern drug industry.

Nevertheless, the scientists have continued research to 
understand how the body can make thousands of different 
antibodies, each one tailor-made to home in and smother a 
specific life-threatening bacteria, virus, poison or other 
foreign intruder, including a piece of graft tissue or 
transplanted organ. Since the mechanism the body uses to 
make antibodies to order is still not fully understood, the 
antibodies cannot yet be synthesised in the test tube. That 
breakthrough waited until 1975, when Dr Cesar Milstein and 
Dr Georges Kohler at the Laboratory of Molecular Biology, in 
Cambridge, discovered how to produce specialised antibodies.

They were not made in a test tube, but by using mice. The 
substances are known as monoclonal antibodies because of 
their method of production. In the way that an animal was 
injected to stimulate an anti-diphtheria antibody, Dr Milstein 
and Dr Kohler injected mice with selected "foreign bodies", 
which the creatures reacted by producing specific antibodies.

These antibodies could be extracted from the mouse, but 
grown in culture only for a short time. The scientists 
overcame this with an idea, which won them a Nobel prize. 
They took from another mouse a different type of cell from 
bone marrow. The cell was chosen because it was a cancerous 
one and therefore capable of reproducing continuously. 
Hence, the scientists created a so-called "hybridoma": a  half-
antibody, half-cancer cell. It provided a limitless supply of 
highly specific monoclonal antibodies, or Mabs. The discovery 
has opened a great range of medical applications.