A multi-institutional study led by researchers at UNC Lineberger Comprehensive Cancer Center, the Salk Institute for Biological Studies, and UC San Diego has uncovered new genetic rules that determine how powerful immune cells\u2014known as CD8 killer T cells\u2014choose between becoming long-lasting, protective defenders or slipping into exhausted, dysfunctional states. The findings reveal new strategies for sustaining immune memory while preserving the ability to fight cancer and infections, with broad implications for immunotherapy and infectious disease research.<\/p>\n
CD8 killer T cells play a central role in immune defense by seeking out and destroying virus-infected cells and cancer cells. However, during chronic infections or within tumors, these cells can gradually lose their killing ability and enter a state known as T cell exhaustion, where they become ineffective.<\/p>\n
\u201cBecause protective and dysfunctional CD8 T cell states can look very similar, we designed this study to ask whether protective immune memory and dysfunction could be genetically separated,\u201d said H. Kay Chung<\/a>, <\/strong>PhD, lead and co-corresponding author and assistant professor in the Department of Cell Biology & Physiology at UNC School of Medicine and UNC Lineberger Comprehensive Cancer Center member. Chung began this research at the Salk Institute before joining UNC. \u201cBy flipping specific genetic switches in T cells, we found that it is possible to restore tumor-killing function without compromising long-term immune protection.\u201d<\/p>\n A key advance of the study was the creation of a detailed atlas of CD8 T cell states, capturing how these immune cells transition across a spectrum from highly protective to deeply dysfunctional.\u00a0\u00a0 \u201cFrom the outset, our goal was to move beyond simply describing T cell states and instead build a predictive framework that allows us to intentionally program them,\u201d Chung said.<\/p>\n \u201cOur long-term goal is to make immune therapies work better by creating clear \u2018recipes\u2019 for designing T cells,\u201d said Susan M. Kaech, PhD, co-corresponding author and professor at the Salk Institute for Biological Studies. \u201cBy building a comprehensive atlas of CD8 T cell states, we were able to pinpoint the molecular factors that define protective versus dysfunctional programs\u2014information that is essential for precisely engineering effective immune responses.\u201d<\/p>\n \u201cThis is a challenging task,\u201d said Wei Wang, PhD, co-corresponding author and professor at UC San Diego. \u201cBecause genes operate within complex regulatory networks, powerful computational tools are essential for identifying the regulators that drive specific T cell states.\u201d<\/p>\n Using advanced laboratory techniques, genetic tools, mouse models, and computational approaches, the researchers analyzed nine distinct CD8 T cell states. They identified specific transcription factors\u2014proteins that control gene activity\u2014that act as molecular switches, steering T cells toward either long-term function or exhaustion.<\/p>\n Among these, the team discovered two transcription factors, ZSCAN20 and JDP2, that had not previously been linked to T cell exhaustion. When these factors were turned off, exhausted T cells regained their ability to kill tumors without losing their capacity for long-term immune memory.<\/p>\n \u201cOur findings should be relevant for both solid tumors and blood-borne cancers,\u201d Chung added. \u201cBut this work may be especially important for solid tumors, where separating protective immune responses from exhaustion remains a major barrier to effective therapy.\u201d<\/p>\n More broadly, the study challenges the long-standing belief that immune exhaustion is an unavoidable consequence of prolonged immune activity.<\/p>\n \u201cBy separating protective and dysfunctional programs, we can begin to design immune cells that are both durable and effective in cancer and chronic infection,\u201d Kaech said.<\/p>\n \u201cThis study shows that we can begin to precisely manipulate immune cell fates and unlock new possibilities for enhancing immune therapies,\u201d Wang added.<\/p>\n Looking ahead, the team will combine advanced laboratory methods with AI-guided computational modeling to develop increasingly precise genetic \u201crecipes\u201d for programming T cells. Building on this foundation, the Chung Lab<\/a> at UNC is developing sophisticated genetic circuits and protein-engineering strategies that enable context-dependent control of these genetic programs, incorporating built-in safety features. This level of precision is essential for advancing therapeutic cell engineering approaches in which immune cells are modified and returned to patients, particularly in cancer immunotherapy applications that leverage stem-cell\u2013based technologies such as adoptive cell transfer (ACT) and chimeric antigen receptor (CAR) T cell therapy.<\/p>\n \u201cIt is important to emphasize that this work was truly a team effort,\u201d Chung said. \u201cIt began with the synergy between Dr. Kaech\u2019s immunology lab at Salk and Dr. Wang\u2019s computational platform at UC San Diego, and after my move to UNC, collaborations here allowed us to strengthen and extend the findings.\u201d<\/p>\n