OBJECTIVETo explore the characteristics and significance of reconstitution of peripheral blood dendritic cells (DCs) after HLA haploidentical hematopoietic stem cell transplantation (HSCT).

METHODSTwenty-one leukemia patients received HLA-haploidentical HSCT. Twelve healthy donors were as normal control. Peripheral blood DC subsets were analyzed by flow cytometry, and correlation between DC reconstitution and acute graft versus host disease (aGVHD) were measured.

RESULTSCompared with healthy subjects, leukemia patients had a significantly decreased proportion and absolute number of DC, myeloid DC (MDC) and MDC1 (0.13% vs 0.76%, 7.89 cells/microl vs 42.66 cells/microl, 0.05% vs 0.65%, 1.52 cells/microl vs 35.56 cells/microl, 0.03% vs 0.44%, 1.33 cells/microl vs 26.70 cells/microl, respectively (P < 0.05). MDC2 and plasmacytoid DC (PDC) were not statistically different between the two groups. The ratio of MDC/PDC was significantly reduced (0.05 vs 4.21) (P = 0.001). After transplantation, the absolute numbers of MDC1, MDC2 and PDC reached to pretransplant levels at day + 14(1.45, 0.32 and 1.60 cells/microl, respectively) (P > 0.05), but remained lower than those of healthy controls up to day + 100. The ratio of MDC/PDC had significantly different between that on + 14 d and pretransplant (1.40 vs 0.50) (P = 0. 024) and reached to healthy controls levels at day +30 (2.00 vs 4.21) (P = 0.602). Patients with higher PDC, DC levels and lower MDC/PDC ratio had lower cumulative incidences of grade II - NV aGVHD as compared with those with lower PDC, DC level and higher MDC/PDC ratio at day + 14(P = 0.006, 0.013 and 0.037, respectively).

CONCLUSIONIn HLA haploidentical HSCT recipients, DC reconstitution is a slow process, possibly contributing to the cumulative incidences of grade II - IV aGVHD.