RT Journal Article SR Electronic T1 Differentiation of a CD4+/CD8αβ+ Double Positive T Cell Population From The CD8 Pool Is Sufficient To Mediate Graft-vs-Host Disease but not Graft-vs-Leukemia Effects JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.01.11.475845 DO 10.1101/2022.01.11.475845 A1 Nicholas J. Hess A1 David P. Turicek A1 Kalyan Nadiminti A1 Amy Hudson A1 Peiman Hematti A1 Jenny E. Gumperz A1 Christian M. Capitini YR 2022 UL http://biorxiv.org/content/early/2022/01/12/2022.01.11.475845.abstract AB Acute graft-vs-host disease (aGVHD) and tumor relapse remain the primary complications following allogeneic hematopoietic stem cell transplantation (allo-HSCT) for malignant blood disorders. While post-transplant cyclophosphamide has reduced the overall prevalence and severity of aGVHD, relapse rates remain a concern. Thus, there remains a need to identify the specific human T cell subsets mediating GVHD pathology versus graft-versus-leukemia (GVL) effects. In xenogeneic transplantation studies using primary human cells from a variety of donors and tissue sources, we observed the development of a mature CD4+/CD8αβ+ double positive T cell (DPT) population in mice succumbing to lethal aGVHD but not in mice that failed to develop aGVHD. The presence of DPT, irrespective of graft source, was predictive of lethal GVHD as early as one week after xenogeneic transplantation. DPT co-express the master transcription factors of the CD8 and CD4 lineages, RUNX3 and THPOK respectively, and produce both cytotoxic and modulatory cytokines. To identify the origin of DPT, we transplanted isolated human CD4 or CD8 T cells, which in turn revealed that DPT only arise from the CD8 pool. Interestingly, re-transplantation of sorted CD8 T cells from GVHD mice did not reveal a second wave of DPT differentiation. Re-transplantation of flow-sorted DPT, CD8 or CD4 T cells from GVHD mice revealed that DPT are sufficient to mediate GVHD pathology but not GVL effects versus B-cell acute lymphoblastic leukemia. Lastly, we confirmed the presence and correlation of DPT with aGVHD pathology in a small cohort of allo-HSCT patients that developed grade 2-4 aGVHD in our clinic. Further understanding of DPT differentiation and pathology may lead to targeted prophylaxis and/or treatment regimens for aGVHD and potentially other human chronic inflammatory diseases.Key PointsHuman DPT cell differentiation is a predictive metric of xenogeneic GVHD lethalityThe origin of DPT are CD8 T cells that gain THPOK expression and CD4 lineage effector functionsDPT cells are sufficient to mediate GVHD pathology but not GVL effectsCompeting Interest StatementC.M.C. reports honorarium from Nektar Therapeutics and Novartis, who had no input in the study design, analysis, manuscript preparation or decision to submit for publication. The authors declare that no other relevant financial conflicts of interest exist.