Naive cytotoxic T lymphocytes spontaneously acquire effector function in lymphocytopenic recipients: A pitfall for T cell memory studies?

Whether memory T cells require persisting antigen for their survival has be en a matter of debate. One prominent view that memory T cells do not requir e persisting antigen is based in part on studies in which T cell population s have been transferred into antigen-free mice. To generate "space" recipie nts were often irradiated; the functional properties of the transfused T ce lls were then evaluated after prolonged periods. In this report we show tha t transferring cytotoxic T lymphocytes (CTL) into irradiated or T and B cel l-deficient hosts results in their proliferation and a change of their acti vation state. Moreover, naive T cell receptor-transgenic CTL specific for t he lymphocytic choriomeningitis virus glycoprotein spontaneously developed cytotoxic effector function under such conditions. Therefore, some of the c onclusions based on transfer of T cell populations into irradiated recipien ts to investigate T cell memory may have to be reevaluated.