Deciphering molecular and functional codes of human memory lymphocytes

Abstract Long-term immunity against infections and effective response to vaccination are dependent on unique feature of lymphocytes referred as “memory generation”. Majority of our understanding is established on murine data and our understanding of human naive to memory differentiation is limited. In our ongoing study we explored epigenetics (DNA methylation and accessible chromatin), transcriptomics (basal, activation and proliferation induced gene expression), intracellular cytokine assay (high-parameter flow cytometry) of naive and memory B and T lymphocytes subsets from the healthy donors. We explored the epigenetic changes associated with memory differentiation. However, relationship between epigenetics and transcriptomic outcomes didn’t explain entirely the properties of being memory or naïve lymphocyte. To understand mechanistic differences, naive and memory cells of B and CD4 T lymphocytes were activated in vitro using either antigen receptor (BCR or TCR crosslinking with antibodies) or PMA+Ionomycin (pan-activation) and assayed for early or late gene expression and for intracellular cytokine profiles. Surprisingly, majority of transcriptomic patterns were similar between naive and memory lymphocytes while their cytokine expression profiles were significantly different. These findings indicate the significant role of translational machinery influencing the memory and naïve lymphocyte functions. Our results are in direction of segregating transcription and translation mediated dependencies of adaptive memory. These findings will provide the foundation for future studies related to dysregulation of memory cell differentiation and function in aging and infections. This project was entirely supported by intramural funding of NIA-NIH.