Is apoptosis a massive process in myelodysplastic syndromes?

We looked for increased apoptosis in fresh bone marrow aspirates in 40 cases of myelodysplastic syndrome (MDS), by detection of DNA fragmentation using TdT incorporation of nucleotides on 3' ends of DNA (TUNEL technique). No DNA laddering was seen. In six cases (15%) the TUNEL technique showed a moderate increase in the percentage of apoptotic cells (2.5-5% in comparison with < 2% in controls). In seven of the 34 patients with normal findings by TUNEL analysis, apoptosis was reanalysed after short-term (18 h) bone marrow culture without inducers of apoptosis. Increased apoptosis was shown in four of the seven cases by morphological analysis and/or the TUNEL technique. Increased apoptosis predominated on erythroblasts in three of them. The percentage of apoptotic cells, however, was < 40% in all samples. Our findings suggest that increased apoptosis can be detected in one half of MDS cases after cell culture. Furthermore, the precise relationship between increased apoptosis of myeloid precursors and cytopenias will have to be more precisely explored in MDS.