[Investigation of plasmacytoid dendritic cell reconstitution and its relationship with cGVHD and relapse after haploidentical hematopoietic stem cell transplantation].

To investigate the characteristics and significance of reconstitution of peripheral blood plasmacytoid dendritic cell (PDC) precursors after allogeneic human leukocyte antigen mismatched/haploidentical hematopoietic stem cell transplantation, and its relationship with chronic graft versus host disease (cGVHD) and relapse, 19 patients with leukemia were enrolled for this study. Peripheral blood dendritic cell (DC) subsets of patients and healthy controls were detected by flow cytometry, and the correlations between reconstitution of DC and cGVHD, relapse were analyzed. The results showed that compared with healthy subjects, patients with leukemia had a significantly decreased proportion and absolute number of myeloid dendritic cell (MDC), MDC1, DC and the ratio of MDC/PDC (P<0.05). There were not statistically different in MDC2 and PDC between patients and healthy subjects. After transplant, all the proportion of WBC and absolute numbers of DC reached to healthy controls levels at 9 months (P>0.05), besides the proportion of PDC which reached to healthy controls levels at 1 year (P=0.494). Compared with levels before relapse, the proportions of MDC1, MDC, DC and the ratio of MDC/PDC were lower, but proportions of MDC2 and PDC were slightly higher after relapse. Patients with a 'high' PDC recovery profile had an improved cumulative incidence of cGVHD in contrast to patients with a 'low' PDC recovery profile on day 120 after transplantation (P=0.007). It is concluded that compared with healthy subjects, de novo leukemia patients have a significantly decreased proportion and absolute number of DC and the ratio of MDC/PDC before haploidentical hematopoietic stem cell transplantation; while ratio of MDC/PDC can be normalized with relative rapidity, the proportions of all DC subsets reached to normal levels on the whole at 9 months after transplantation, and also recovery level of DCs is correlated with occurrence of cGVHD and relapse.