Low blood dendritic cells in chronic myeloid leukaemia patients correlates with loss of CD34+/CD38- primitive haematopoietic progenitors.

Myeloid and plasmacytoid dendritic cells (MDC, PDC) play a key role in the initiation of immune responses. We found a reduction of DC subsets among 20 chronic myeloid leukaemia (CML) patients in chronic phase (MDC, mean, 0.10% +/- 0.10, P = 0.02; PDC, mean, 0.11% +/- 0.08, P = 0.006 versus controls). The maintenance of blood DC correlated with the presence of high percentages of circulating CD34+/CD38- progenitors that were able to give rise in vitro to CD1a+ DC. The reduced DC numbers may contribute to leukaemia escape from immune control and restoration of DC may be a goal for CML immunotherapy.