Dendritic Cells in Bone Marrow at Diagnosis and after Chemotherapy in Adult Patients with Acute Myeloid Leukaemia

Dendritic cells (DCs) develop in the bone marrow from haematopoietic progenitor cells. Two subsets, plasmacytoid DC s (p DC s) and myeloid DC s (m DC s), have been identified. Little is known regarding DC levels in bone marrow of patients with acute myeloid leukaemia ( AML ) before and after chemotherapy. We investigated relative p DC and m DC levels in bone marrow from 37 hospital controls and 60 patients with AML [at diagnosis, complete remission ( CR ) and follow‐up] using four‐colour flow cytometry. The p DC immunophenotype was characterized as lin‐/HLA‐DR+/CD123 +  and m DC as lin‐/ HLA ‐ DR +/ CD 11c+. In 69% of patients with AML , no DC s were detected at diagnosis. At CR , m DC levels were the same in patients with AML and hospital controls while p DC levels were slightly lower. There was no association between minimal residual disease or survival rates and DC levels. Patients with low m DC levels at CR were more likely to suffer from complicated infections, although the difference was not statistically significant. Altogether, there was a profound decrease in DC levels in patients with AML at diagnosis. DC levels increased at CR and were higher than in hospital controls after post‐remission therapy, suggesting that DC s recover after repeated chemotherapy. There may be an association between m DC levels and infectious complications.