Such traits -- whether of viruses, ragweed pollen or cancer -- are called antigens.
Antigens stick out from cells like molecular signposts, saying kick me to the immune systems soldiers.
Finding the antigens is like searching a beach for a particular grain of sand.
For some reason, the antigens on tumor cells dont grab the soldiers attention strongly enough.
If all goes well, the beefed-up antigens will then spark an immune assault on the tumor.
In the absence of foreign antigens, a juiced-up immune system sometimes can't stop attacking its own body.
So the scientists extract the antigens from tumors, purify them, multiply them and then inject them into the patient.
"At best using single antigens would leave many more children unprotected for extended periods and would raise the likelihood of epidemics, " he said.
Several biotech and pharmaceutical companies are trying to identify tumor-specific antigens.
New York-based ImClone Systems, for instance, is targeting lung cancer antigens.
The antibody was then carefully drawn across the surface at a height that allowed it to recognise and bind to any antigens in its path.
But what causes one person to become sensitive to these indiscriminate antigens floating through the air, while another sails through life with dry eyes and clear sinuses?
They found that T cells went into action when CD-2 bound itself to a counterpart molecule, LFA-3, on the surface of cells that escort antigens to their death.
The researchers' thinking went as follows: antibodies are designed to lock on to specific parts of larger molecules called antigens, just as a key fits a particular lock.
For example, a thorough review published inPediatrics in 2002 showed that infants today are exposed to fewer antigens than they were 40 years ago, due to better vaccine formulations.
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After scanning across the whole surface, having previously compiled a relief map of the surface in the usual way, the researchers were able to draw up a map of the binding sites and pinpoint the positions of the antigens to within two or three nanometres.
Thimerosal prevented bacteria and fungi from growing in the vaccine (and many other products, for example while it is no longer used in vaccines it is still used in tatttoo inks, nasal solution products, opthalmic drugs, eye products, ear products, toxoids, antivenins, immunoglobulins, and skin test antigens).
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