Improved Vδ2⁺ T cells recovery correlates to reduced incidences of mortality and relapse in acute myeloid leukemia after hematopoietic transplantation

Acute myeloid leukemia (AML) patients can benefit from allogeneic hematopoietic cell transplantation (alloHCT) and achieve long-term remission. Recovery of T cell quantity and quality is critical to reduce the incidences of life-threatening complications after alloHCT. Although the general recovery level of γδ T cells is recognized to be associated with outcomes of patients who suffered from various hematological diseases and received alloHCT, the correlation between γδ T cell subsets and the prognosis in AML patients following transplantation remains to be investigated. In the current study, the recoveries of T cell subpopulations in 103 AML patients were dissected at different time points after haploidentical HCT (haploHCT). Statistical analyses showed that the absolute number of Vδ2⁺ T cells on day 90 was an independent risk factor for predicting 2-year OS in AML patients following haploHCT. The survival advantage from the improved recovery of day-90 Vδ2⁺ T cells was attributed to reducing the infection-related mortality. Consistently, lower 2-year non-relapse mortality was found in recipients with higher day-90 levels of Vδ2⁺ T cells. Notably, day-270 Vδ2⁺ T cell numbers reversely correlated to both 2-year and 5-year probabilities of relapse in this scenario. These results highlighted the significant correlation of Vδ2⁺ T cells recovery with long-term survival and relapse after alloHCT, suggesting that Vδ2⁺ T cells-based immune strategies may help control infectious complications and leukemia recurrence in AML patients.