Salk Institute researchers have created a detailed epigenetic map of human immune cells that reveals how inherited traits and past exposures shape immune responses.[1][2] This research explains why the same virus barely infects one person while sending another to the hospital.[1] They analyzed immune cells from 110 people and compared four main types: T-cells, B-cells, monocytes and natural killer cells.[2] The study distinguished genetically inherited changes (gDMRs) from those caused by life experiences (eDMRs), such as infections, vaccines or environmental chemicals.[1][2][4] gDMRs are found mainly in stable gene regions, particularly in long-lived T- and B-cells, while eDMRs in flexible regulatory regions controlling rapid responses.[1][2] The database was published in Nature Genetics on January 27, 2026 and is used for personalized treatments and diagnosis of infectious and genetic diseases.[1][2][4] Epigenetic marks can help determine the cause and severity of diseases.[1][2]