Regularly infusing the body with large numbers of T cell immune cells has the potential to help with a range of issues, given that the immune system declines with age: recent research "provides new insights into how our immune system produces T cells, a type of white blood cell that is an essential part of the body's immune surveillance system for fighting infection. The findings pave the way for a new means of making purified T cells, which gets over one of many hurdles faced in the use of T cells in regenerative medicine and transplantations, and in addition will open up new avenues of research and applications in drug and toxicity testing in industry. ... It reveals for the first time how immature T cells can be grown without the need for supporting 'feeder' cells - these cannot be easily separated from T cell preparations, reducing their suitability for transplantation in the clinic. This may advance the field of regenerative medicine. ... This technology could enable the production of T cells for clinical applications such as their transplantation into immuno-compromised individuals."