The number of donor CD3+ cells is the most important factor for graft failure after allogeneic transplantation of CD34+ selected cells from peripheral blood from HLA-identical siblings

Abstract

This study analyzed the characteristics of 257 HLA-identical sibling transplants of granulocyte colony-stimulating factor- mobilized peripheral blood progenitor cells depleted of T cells by CD34+ positive selection (allo-PBT/CD34+) for their effect on the incidence of graft failure. Twenty-four patients developed graft failure (actuarial probability, 11%; 95% confidence interval, 7.1-14.9). Prognostic factors considered were sex and age of donor and recipient, donor-recipient blood group compatibility, diagnosis, disease status at transplant, conditioning regimen, cytomegalovirus serology, number of CD34+ and CD3+ cells infused, and cryopreservation. The major factor associated with graft failure was the number of CD3+ cells in the inoculum. Twenty-three of 155 patients receiving a T-cell dose in the graft less than or equal to 0.2 x 106/kg experienced graft failure, compared with only one of 102 patients receiving more than 0.2 x 106/kg (actuarial probability 18% vs 1%, respectively; P = 0001). The actuarial probability of graft failure progressively increased as the number of CD3+ cells in the graft decreased, which was determined by grouping the number of CD3+ cells in quartiles (log-rank P = .03; log-rank for trend P = .003). In the multivariate analysis by the proportional hazard method, 2 covariates entered into regression at a significant level: CD3+ cells less than or equal to 0.2 x 106/kg (risk ratio = 17; P