Single-cell profiling of circulating immune cells in healthy older adults

To characterize immune signatures of aging, we recruited healthy, non-frail older adults (aged 64 and above) and profiled their peripheral blood mononuclear cells via 5’ single-cell RNA sequencing along with paired T-cell receptor (TCR) sequencing. CMV serostatus was quantified using IgG ELISA. Integrating these datasets, we identified multiple subsets of T cells associated with CMV seropositivity. In addition, we uncovered CMV-specific TCR clones in CMV-positive individuals. Specifically, CMV-positive older adults displayed reduced diversity of TCRs in GZMK+ CD8+ T cells, Th1, and CD4+/CD8+ TEMRA subsets. This data was also used to test the performance of CMVerify, a machine learning classifier, in predicting CMV serostatus. Overall, this study uncovers novel alterations in immune cells associated with latent CMV infection in older adults.