The elderly mount a poorer immune r

The elderly mount a poorer immune response to influenza vaccinationthan do the young (29), and this may contribute to the significant morbidity and mortality caused by influenza virus in the elderly, even among vaccinated individuals (30). Here we report that mTOR inhibition reinitiated B cell development and enabled aged mice to mount a robust antibody response capable of protecting them against lethal influenza infection. Our data suggest that rapamycin,or possibly other inhibitors of mTOR, can be used to rejuvenate HSCs for better immune protection.We also found that 6 weeks of rapamycin treatment extended mouse life span, consistent with a recent study that showed that continuously feeding old mice with rapamycin extended their life span (16). Although rapamycin has been used as an immune suppressant in transplantation (23), treatment with rapamycin during infection can paradoxically induce a more effective memory T cell response (31)