biostudies-literatureKeller MDCalifornia Institute for Regenerative MedicineCalifornia Institute for Regenerative Medicine (CIRM)2749https://www.ebi.ac.uk/biostudies/studies/S-EPMC10980733biostudies-literatureUnknown15(1)Virus-specific T cells (VST) from partially-HLA matched donors have been effective for treatment of refractory viral infections in immunocompromised patients in prior studies with a good safety profile, but rare adverse events have been described. Here we describe a unique and severe adverse event of VST therapy in an infant with severe combined immunodeficiency, who receives, as part of a clinical trial (NCT03475212), third party VSTs for treating cytomegalovirus viremia following bone marrow transplantation. At one-month post-VST infusion, rejection of graft and reversal of chimerism is observed, as is an expansion of T cells exclusively from the VST donor. Single-cell gene expression and T cell receptor profiling demonstrate a narrow repertoire of predominantly activated CD4⁺Nature communicationsSecondary bone marrow graft loss after third-party virus-specific T cell infusion: Case report of a rare complication.PMC10980733CLIN2-10392Pulsipher MAQayed MKeller MDPai SYParikh SChandrakasan SAllen EKJensen-Wachspress MASchattgen SAGottschalk SLang HTanna JBollard CMBerger SILazarski CAThomas PGHanley PJfalseSecondary bone marrow graft loss after third-party virus-specific T cell infusion: Case report of a rare complication.Virus-specific T cells (VST) from partially-HLA matched donors have been effective for treatment of refractory viral infections in immunocompromised patients in prior studies with a good safety profile, but rare adverse events have been described. Here we describe a unique and severe adverse event of VST therapy in an infant with severe combined immunodeficiency, who receives, as part of a clinical trial (NCT03475212), third party VSTs for treating cytomegalovirus viremia following bone marrow transplantation. At one-month post-VST infusion, rejection of graft and reversal of chimerism is observed, as is an expansion of T cells exclusively from the VST donor. Single-cell gene expression and T cell receptor profiling demonstrate a narrow repertoire of predominantly activated CD4⁺2024-01-01T00:00:00Z2024 Mar2026-07-16T12:04:38.36Z2025-04-19T10:15:13.036ZS-EPMC109807333855346110.1038/s41467-024-47056-3