The aging immune system is misconfigured, overpopulated by too many of the wrong sorts of immune cell, while having too few useful cells left to perform the important jobs - such as resisting infections, attacking cancers, and removing senescent cells, for example. One approach to dealing with this problem is to destroy the unwanted cells, and there's evidence for at least some parts of the immune system to show that this is beneficial. Another approach is to use biotechnology to expand the population of useful cells, and this recent release fits into that line of work: "Aging brings about a selective decline in the numbers and function of T cells - a type of white blood cell involved in the immune system's response to infection - and T cells that survive the longest may better protect against infections such as the flu ... The finding may lead to targeting these cells with vaccinations that increase their number and improve protection against disease in older adults. ... The decline in immune function with age is viewed as the most important contributing factor to older adults' increased susceptibility to infections and decreased responses to vaccinations. ... We have discovered that aging brings about selective attrition of those T cells that defend us against new infections that we have not encountered before. Not all T cells age the same and the ones that will survive the longest have special features. ... Finding ways to expand them is our next and final challenge, and our team [should] be able to achieve that in the next few years."