Influence of bone marrow graft lymphocyte subsets on outcome after HLA-identical sibling transplants

Objective The aim of this study was to analyze bone marrow lymphocyte subsets and CD34 cell dose and their influence on the outcomes of bone marrow transplantation. Materials and Methods Forty-eight patients (median age 30 years, range 5–54) receiving HLA-identical sibling bone marrow transplantation for hematologic malignancies were analyzed. Results Median number (range) of nucleated cells and CD34+ cells infused were 2.4 (0.4–6.0) × 108/kg and 3.5 (0.5–13.0) × 106/kg, respectively. Probability of neutrophil recovery was 97%. In a multivariate analysis, time to neutrophil recovery was shortened when a higher number of CD3/CD8 cells was infused (≥1.0 × 107/kg) (hazard ratio [HR] = 2.13, p = 0.018); when the patient was female or had negative cytomegalovirus serology (HR = 2.03, p = 0.03; HR = 0.41, p = 0.009; respectively). The incidence of grade II to IV acute graft-vs-host disease (GVHD) was 47%. Infusion of >1 × 107 CD4 infused/kg increased the risk of acute GVHD (HR = 2.86, p = 0.03). Nineteen of 40 patients at risk experienced chronic GVHD, the risk of which was increased by diagnosis of chronic leukemia (p = 0.03), <2.0 × 108 nucleated cells infused/kg (p = 0.05), and a low number of all lymphocyte subsets, except CD19. Estimated 3-year survival rate was 54%. Risk of death was increased in patients receiving <3.5 × 106CD34 infused/kg (HR = 0.37, p = 0.02). Only six patients relapsed. Conclusions A high cell dose of CD3/CD8 is associated with faster neutrophil recovery, whereas a high cell dose of CD4+ cells increases the incidence of acute GVHD. A high number of nucleated cells and CD34+cells infused was associated with decreased risk of chronic GVHD and improved survival, respectively.