IT鈥橲 the biological equivalent of a turncoat. A drug used to stop immune cells from gobbling up transplanted organs and bone marrow has been caught boosting the immune response to a virus in mice and monkeys. It might now be used to enhance vaccines against cancer and other diseases.
Transplant recipients take because it blocks the production of a range of different immune cells. But when and colleagues at Emory University School of Medicine in Atlanta, Georgia, gave the drug to mice infected with a virus, to probe its effects on specific parts of the immune system, they found it can have another effect. The mice produced more memory T-cells, which kick in when bugs come back, than mice not given the drug. 鈥淲e were completely surprised,鈥� says Ahmed.
The mice treated with rapamycin also ended up with better quality memory T-cells than the control mice. These cells could respond faster and more effectively to a future infection with the same virus (Nature, ). Rapamycin had the same effect in mice and rhesus macaques when given alongside a vaccine.
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Although the team did not measure it specifically, Ahmed suspects that the drug was also suppressing parts of the immune system in the mice and monkeys, just as it does in transplant recipients. To use rapamycin as a vaccine booster in people will mean finding a dose that raises memory T-cell count and quality but keeps immunosuppression to a minimum, says Ahmed.
