Immune drug 'boosts vaccines'29th June 2009
A drug commonly used to suppress the immune system following transplants may also boost the efficacy of certain vaccines, a study shows.
The immunosuppressant rapamycin is usually indicated to stop patients' bodies from rejecting donated organs.
A US-based research team has now found in tests on monkeys and mice that the drug also enhanced the animals' response to experimental vaccines.
Published in the journal Nature and written by a team of scientists from Emory University, the report said there were hopes now for a possible new generation of potent vaccines.
The results hinged around a protein known as mTOR, which is a key factor in controlling cell growth, and which is inhibited by rapamycin.
Virus-infected mice given a dosage of rapamycin - thereby having their mTOR protein switched off - showed a better immune response than those that did not.
Another key component of the findings was the role played by 'memory' T cells, which remember infections that the body has dealt with in the past.
The researchers showed that rapamycin also boosted memory T cell responses to experimental vaccines in monkeys and mice.
They concluded that mTOR also plays a role in regulating the generation of memory T cells.
Vaccine manufacturers could potentially harness this knowledge to create memory T cells, which could potentially make for very powerful vaccines against chronic infections and tumours.
Many vaccines need multiple vaccinations to obtain enough immunity to overcome infections because immunity after a single shot of vaccination is often too weak to fight with infection, according to researcher Koichi Araki.
Araki said rapamycin could be administered at the same time as a vaccine to boost its efficacy.
Jenner Institute director Adrian Hill said very few vaccines currently licensed worked in such a manner.
But new vaccines under development, including those for HIV, cancer and malaria, might use such an approach.
He speculated that the finding might be useful for trial with some experimental cancer vaccines.
Hill added that animals and humans responded very differently to immunosuppressants, however.
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Title: Immune drug 'boosts vaccines'
Author: Luisetta Mudie
Article Id: 11929
Date Added: 29th Jun 2009