Virus-induced CD8(+) T cell clonal expansion is associated with telomeraseup-regulation and telomere length preservation: A mechanism for rescue from replicative senescence

In acute infectious mononucleosis (AIR I), very large clones of Ag-specific CD8(+) effector T cells are generated. Many clones persist as memory cells , although the clone size is greatly reduced. It would be expected that the large number of cell divisions occurring during clonal expansion would lea d to shortening of telomeres, predisposing to replicative senescence. Inste ad, we show that clonally expanded CD8(+) T cells in AIM have paradoxical p reservation of telomere length in association, with marked up-regulation of telomerase, We postulate that this allows a proportion of responding T cel ls to enter the memory pool with a preserved capacity to continue dividing so that long-term immunological memory can be maintained.