Origin of CD8⁺ effector and memory T cell subsets.

Differentiation of CD8 T cells into diverse effector- and memory populations is an important feature of these cells and necessary for the development of protective immunity against pathogens and certain tumors. In this work we analyzed the differentiation of naïve antigen-specific CD8 T cells after adoptive transfer of single cells into wildtype mice. With the help of this novel tool we could show that after activation, a single CD8 T cell harbors the potential to differentiate into all major subsets. Interestingly, we found in addition that the differentiation patterns of transferred and polyclonal endogenous T cells was almost identical in individual mice. This implicates that factors operative during the expansion phase play an important role in the development and shaping of CD8 T cell responses. These results are important for the development of more effective T cell-based vaccines and for adoptive immunotherapy