Megakaryocytic Ploidy in Myelodysplastic Syndromes

Abstract

The megakaryocytic ploidy was microfluorometrically measured in 12 normal controls and 15 myelodysplastic syndrome (MDS) patients using DAPI (4',6-diamidino-2-phenylindole) staining after destaining of the Wright-Giemsa (WG) stain. MDS patients had slightly more immature megakaryocytes when compared with normal controls. The megakaryocytic ploidy distribution had a peak at 16N in normal controls, at 8N in the 11 of the 15 MDS patients, and at 4N in the remaining 4 patients, which is suggestive of impaired polyploidization in MDS patients. In MDS, micromegakaryocytes were shown not to be immature but much more impaired in polyploidization than non-micromegakaryocytes. However, there was no difference in the megakaryocytic ploidy pattern among the type of the modification of Feinendegen' classification in each case for both the normal controls and the MDS patients, suggesting that the megakaryocytic ploidy is probably determined at the maturation level of the megakaryoblasts or the precursor cells. The study of megakaryocytic ploidy before and after therapy in the case of refractory anemia with excess of blasts might suggest that the remission of MDS patients might be qualitatively different from that seen in acute leukemia patients. Furthermore, the DNA histogram of the megakaryocytes from one of the two MDS patients obtained by the new method, which is able to determine the amount of DNA in the immunologically identified megakaryocytes microfluorometrically, using the monoclonal anti-glycoproteins IIb/IIIa antibody on bone marrow smears, showed a shift towards small ploidy compared with those defined on the basis of WG staining. This finding indicates that the micromegakaryocytes or the megakaryoblasts which could not be identified morphologically can be identified immunologically.(ABSTRACT TRUNCATED AT 250 WORDS)

The expression of minichromosome maintenance protein‐2 in normal and abnormal megakaryocytes and comparison with the proliferative marker Ki‐67

“…In MPDs, such as essential thrombocythaemia and myelosclerosis, high ploidy values (up to 512n) are noted. On the contrary, in myelodysplasia, megakaryocyte nuclei are small and generally of low ploidy (Kobayashi et al , 1993; Jacobsson et al , 1996). It is possible to view the megakaryocytic biology in disease states as:…”

Comparison of the DNA content of megakaryocytes identified immunologically with that identified morphologically

“…They were then mounted with a fresh DAPI staining solution and, to prevent the staining solution from evaporating, fingernail enamel was applied around the coverslip. Immunofluorescent staining of glycoproteins (GP) IIb and DAPI staining As in our previous report (Kobayashi et al 1993), bone marrow smears were fixed with a buffered acetone-formalin solution (20 mg Na 2 HPO 4 , 100 mg KH 2 PO 4 , 30 ml H 2 O, 45 ml acetone, 25 ml formalin, pH 6.6) for 30 s, and then washed in water. These smears were immersed in a phosphate-buffered solution (PBS) pH 7.2 for 15 min and immunostained for 30 min at 37°C using mouse monoclonal anti-GPIIb antibodies (CD41b, TP80; Nichirei, Tokyo, Japan) diluted 10 times in PBS.…”

“…However, it is sometimes difficult to identify micromegakaryocytes by morphological measurements alone and this method is both time and energy consuming. We therefore devised a new microfluorometric method for determining the DNA content of megakaryocytes identified immunologically in bone marrow smears (Kobayashi et al 1993). In this paper we initially studied whether the DAPI fluorescence intensity was proportional to the DNA content of megakaryocytes identified immunologically.…”

Deletion of 5q31 is observed in megakaryocytic cells in patients with myelodysplastic syndromes and a del(5q), including the 5q- syndrome

“…Even though morphologic abnormalities of megakaryocytes are characteristic in the 5q‐ syndrome, little is known about the cytogenetic behavior of these cells. Some studies showed that micromegakaryocytes in MDS were morphologically mature, but had impaired polyploidization (4N or 8N), whereas normal megakaryocytes were 16N (Kobayashi et al, 1991, 1993, 1995). Recently, a FISH study using centromeric probes specific for chromosomes 7 and 8, and confocal laser scanning microscopy, proved that megakaryocytes are involved in the malignant clone (Van Lom et al, 1999).…”