Impact of aging on cell-to-cell transcriptional variability during immune stimulation

We explored how aging impacts transcriptional dynamics using single-cell RNA-sequencing to profile hundreds of CD4+ T cells from young and old mice from two divergent species. In young animals, immunological challenge drives a conserved transcriptomic switch from highly variable to tightly regulated gene expression, characterized by a strong up-regulation of a core activation program, coupled with a decrease in cell-to-cell variability. Aging significantly perturbed the activation of this core program, and increased expression heterogeneity across the population of cells in both species.