Catalysts for the body

british immunologists have developed artificial antibodies that help in setting the body's immune system into action. Antibodies are y -shaped watchmen of the immune system that identify harmful cells and infectious organisms. They simultaneously get hold of diseased cells and immune system proteins to initiate a full-scale attack on invading organisms ( New Scientist , Vol 155, No 2090).

For a long time, immunologists had been trying to genetically engineer artificial antibodies for treating cancer and other complications. But they had not found much success as it had been difficult to construct antibodies with tails and claws. Most of the antibodies available today, only possess claws, which can grab the harmful cells and infectious organisms but prove to be little efficient in mobilising the immune system to fight with the target.

Greg Winter, Philipp Holliger and Roland Kontermann of the British Medical Research Council's Laboratory of Molecular Biology, Cambridge, fused two sets of antibody claws to form a diabody. One set of claws grabs the diseased cell, marking it out for destruction, while the other acts like the tail, sounding the alarm. As diabodies are smaller than antibodies, they can penetrate tissues easily.

When natural antibodies capture invaders, their tails attract a mixture of proteins in blood serum that destroy captured cells. These infecting agents are then digested by the white blood cells.

The immunologists created another diabody using claws designed to kidnap natural antibodies floating in the blood stream. The idea was to use the captive antibody, which has a tail, to trigger an immune response. Again the experiment was successful. The diabodies captured the cancer cells and then the while blood cells in human serum rapidly destroyed the target.

The team now plans to study whether the diabodies can combat disease in animals. If the trial is successful then the scientists will start trials of the antibodies on human body.

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