CD28−CD8+ T cells do not contain unique clonotypes and are therefore dispensable

Highly differentiated CD28− effector T cells which accumulate in a variety of diseases and also with increasing age contribute to inflammatory processes, limit immunological space and diversity, and are associated with immunological dysfunction and reduced responses to vaccination. Elimination of CD28− T cells has been suggested as a measure for immunological rejuvenation but may lead to the loss of important T cell specificities. Using T cells specific for the immunodominant CMV-derived epitope NLVPMVATV as a model, we show that the same clonotypes are present in CD8+CD28+ naïve/early memory and CD8+CD28− effector T cells. Therefore, CD28− cells do not seem to contain clones which are not present in the residual population. The elimination of effector T cells would not lead to the loss of important specificities, as relevant clonotypes could be recruited and propagated from naïve or early memory T cell subsets in the case of exposure to pathogen.