A common immunosuppressive drug can enhance immune responses to experimental vaccines in mice and monkeys. The counterintuitive findings, reported online in Nature, could offer a new approach for boosting vaccines against infectious diseases and cancer.
Rapamycin is commonly given to transplant recipients to stop their own immune systems from rejecting their new organ. Among its many effects the drug inhibits a particular signalling pathway called mTOR, but it was not known how this would affect immune responses.
Rafi Ahmed and colleagues found that when they switched off mTOR using rapamycin in virus-infected mice, the animals actually produced a better immune response. In particular, the treatment seemed to boost the number of 'memory' T cells - the cells that are responsible for remembering infections they have encountered before. The team went on to show that rapamycin could improve memory T-cell responses to experimental vaccines in both mice and monkeys.
The study identifies mTOR as an important molecular pathway in regulating the generation of memory T cells. This is important because memory T cells are a critical component of protective immunity and making them is a major goal of vaccines against chronic infections and tumours.
Rafi Ahmed (Emory University School of Medicine, Atlanta, GA, USA)
Abstract available online.
(C) Nature press release.
Message posted by: Trevor M. D'Souza