Precision for Medicine 1 article published in JoVE Immunology and Infection Determination of Immune Cell Identity and Purity Using Epigenetic-Based Quantitative PCR Suman K. Pradhan1, Jerry Guzman1, Carl Dargitz1, Stephanie Switalski2, Mark Landon1, Sven Olek3, Bjoern Samans3, Ulrich Hoffmueler3, Uma Lakshmipathy1 1Cell Biology, Life Sciences Solutions, Thermo Fisher Scientific, 2California Polytechnic State University (Cal Poly), 3Epiontis GmbH, Precision for Medicine Here we describe a robust method of determining immune cell identity and purity through epigenetic signatures detected using quantitative PCR (qPCR). DNA demethylation at a specific locus serves as a unique identifier for a particular cell type and allows for identification of CD8+, regulatory, or Th17 T cells.