Dendritic cell count in the graft predicts relapse in patients with hematologic malignancies undergoing an HLA-matched related allogeneic peripheral blood stem cell transplant.

We investigated the impact of the number of infused and reconstituted immunocompetent cells including dendritic cells (DCs) on clinical outcome of patients with hematologic malignancies undergoing an allogeneic peripheral blood stem cell transplantation. Sixty-nine consecutive patients with hematologic malignancies were included in the analysis. The median age of the cohort was 32 years (range: 2-62 years) and there were 39 (57%) males. Twenty-one (30%) patients relapsed with a cumulative incidence of 44 % +/- 14% at a median follow up of 28 months. On a multivariate analysis, a high plasmacytoid dendritic cell (PC) content in the graft was associated with higher risk of relapse. The patients were further categorized based on the median PC counts in the graft as high (> or =2.3 x 10(6)/kg) and low (<2.3 x 10(6)/kg) groups. The baseline characteristics of these 2 groups were comparable. The group that had a high PC content in the graft had significantly higher risk of relapse and lower overall survival (OS) and event-free survival (EFS). Our data suggests that PC content in the graft predicts clinical outcomes such as relapse and survival in patients with hematologic malignancies undergoing an allogeneic HLA matched related peripheral blood stem cell transplantation. There is potential for pretransplant manipulation of this cellular subset in the graft.