This Medical News Today piece on reprogramming the activity of T cells in our immune system is focused on HIV and hepatitis as applications, but this misses the most obvious use for those of us interested in healthy life extension. We know that - as a result of past chronic infections "using up" capacity - the ability of T cells to react to new threats declines with age. The declining immune system plays a large part in age-related frailty, suffering and eventual death. If scientists have a way to reprogram this part of the immune system, then new therapies could rejuvenate its effectiveness. From the article: "The concept that T cell deletion and inactivation is neither an inevitable nor permanent consequence of persistent viral infection - that it is reversible - and that its reversal leads to control of viral infection, should have important implications for the future design of therapeutic approaches to resurrect T cell responses."