DNA content of granulocytes, monocytes, and lymphocytes in the bone marrow smears of patients with myelodysplastic syndromes

Recently, we have reported a high incidence of DNA hypodiploidy defined as DNA index (DI) in blasts/promyelocytes from 39 patients with myelodysplastic syndromes (MDS) found to be without a relationship to cytogenetics. In the present study the DNA content (DI) in granulocytes, monocytes, and lymphocytes measured in the same bone marrow smears from the above patients are reported. DNA hypodiploidy was found in mature cells, not only in myeloid cells (granulocytes and monocytes) but also in lymphocytes. A lower mean DI in each cell type of patients compared to controls was found. Pairwise comparison of the mean DI (±SE) in 32 patients with normal (n = 22) and abnormal (n = 10) cytogenetics and controls (n = 8) showed a significantly (P < 0.01) lower value for each group of patients, respectively, in all cell types. No difference was found between the two groups of patients. Presence of weak-Feulgen stained nuclei (DI < 0.40) in granulocytes and monocytes was more pronounced in patients expressing DNA hypodiploid immature cell populations, but only occasionally in lymphocytes, suggesting a link to an apoptotic event and intramedullary cell death. DNA hypodiploidy is shown to be a common feature even in mature cell populations in MDS bone marrows. Clonality, by means of DNA content, appears reasonable as regards the granulocytes and monocytes. DNA hypodiploid lymphocytes, on the other hand, might be small blasts (stem cells) or dying cell populations of unknown origin.