Rapid helper T-cell recovery above 200 × 10⁶/l at 3 months correlates to successful transplant outcomes after allogeneic stem cell transplantation

The current study evaluates the role of quantitative measurement of peripheral lymphocyte subsets, especially CD4⁺ helper T-cell recovery, in predicting transplant outcomes including overall survival (OS) and non-relapse mortality (NRM) after allogeneic stem cell transplantation. A total of 69 allogeneic recipients were included with following diagnoses: acute myeloid leukemia 42, acute lymphoblastic leukemia 5, chronic myeloid leukemia 15, non-Hodgkin's lymphoma 5 and high-risk myelodysplastic syndrome 2. The peripheral lymphocyte subset counts (CD3⁺ T cells, CD3⁺4⁺ helper T cells, CD3⁺8⁺ cytotoxic T cells, CD19⁺ B cells, and CD56⁺ natural killer cells) were measured at 3, 6 and 12 months. The CD4⁺ helper T-cell reconstitution at 3 months was strongly correlated with OS (P<0.0001), NRM (P=0.0007), and opportunistic infections (P=0.0108) at the cutoff value of 200 x 10^6/l CD4⁺ helper T cells. Rapid CD4⁺ helper T-cell recovery was also associated with a higher CD4⁺ helper T-cell transplant dose (P=0.006) and donor type (P<0.001). An early CD4⁺ helper T-cell recovery at 3 months correlated with a subsequent faster helper T-cell recovery until 12 months, yet not with B-cell recovery. In a multivariate analysis, rapid recovery of CD4⁺ helper T cells at 3 months was a favorable prognostic factor together with higher CD34⁺ cell transplant dose in terms of OS (P=0.001) and NRM (P=0.005).