Decreased HLA-DR+CD3+ T cells three months after allogeneic stem cell transplantation predict severe chronic GvHD and transplant-related mortality.

Chronic graft vs host disease (cGvHD) is a major late determinant of transplant related mortality (TRM) after allogeneic hematopoietic stem cell transplantation (HSCT). We investigated the predictive value of peripheral blood activated HLA-DR+CD3+ T cells as a novel biomarker. In total, 107 patients were included in this retrospective analysis. Peripheral blood HLA-DR+CD3+ T cells were measured by flow cytometry 3 mo after HSCT. A HLA-DR+CD3+ T cell count <140 cells/µL at month 3 after HSCT correlated significantly with an increased TRM. A HLA-DR+CD3+ T cell count <100 cells/µL was associated with a higher rate of cGvHD grade 2 to 3. Subgroup analyses revealed significant results for TRM and cGvHD grade 2 to 3 for patients with a reduced intensity conditioning. In summary, low HLA-DR+CD3+ T cells in the peripheral blood 3 mo after HSCT may represent a novel biomarker to identify patients with an increased risk for TRM and cGvHD grade 2 to 3.