IMAGINE being able to instantly round up your existing supply of antibodies to fight any disease you choose. That scenario is a step closer to reality following the creation of molecules that transform mouse antibodies into potent cancer killers.
Most vaccines 鈥� like those for measles or smallpox 鈥� prompt the immune system to build a standing army of antibodies against a virus or bacterium by injecting a deactivated version of the bug into the body.
But it can take weeks or months to build up immunity, and you have to catch people before they get infected. What鈥檚 more, the approach doesn鈥檛 always work 鈥� cancer and HIV vaccines have proved elusive.
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So instead, Carlos Barbas and colleagues at the Scripps Research Institute in La Jolla, California, have developed dumb-bell shaped 鈥渁daptor鈥� molecules that bind mouse antibodies to proteins on the surface of disease-causing agents, redirecting the antibodies鈥� killing focus. In an earlier experiment they attached these molecules to a single kind of antibody in the lab, and injected these 鈥渞etrofitted鈥� antibodies into the mouse to kill tumour cells.
Now they have demonstrated that these synthetic molecules can bind many kinds of antibodies to cancer cells inside mice and reduce the size of implanted human tumours.
Four weeks after the molecules were injected, the colon tumours had shrunk by up to 90 per cent, and melanomas by 78 per cent (Proceedings of the National Academy of Sciences, ).
鈥淔our weeks after the molecules were injected, the colon tumours had shrunk by 90 per cent鈥�
Barbas now wants to try customising the molecules to bind antibodies to HIV, rather than to tumours. They might also be customised to fight flu, malaria or to protect against bioterror agents.
鈥淭his is a highly ingenious way to induce an instant 鈥榲accine effect鈥�,鈥� says Peter Palese, who studies RNA viruses at the Mount Sinai School of Medicine in New York.
However, one disadvantage is that the adaptors only stay attached for three to four days. This means that for treatment to be effective booster shots are required.
