CA2+ MG2+-DEPENDENT ENDONUCLEASE IN MARROW CD34 POSITIVE AND ERYTHROID-CELLS IN MYELODYSPLASIA/

Endonucleases capable of producing internucleosomal DNA cleavage are o ne of the key enzymes in apoptosis. We examined endonuclease activitie s contained in nuclei of CD34(+) and erythroid cells in the bone marro w (BM) from 12 patients with the myelodysplastic syndromes. The levels of Mg2+-dependent and acidic endonucleases showed little changes as c ompared with those from normal BM. By contrast, the level of Ca2+/Mg2-dependent endonuclease was appreciably higher in MDS erythroid cells than normal counterparts, although the activity varied markedly in CD3 4(+) and erythroid cells. Our results suggested that Ca2+/Mg2+-depende nt endonuclease is related to ineffective erythropoiesis in MDS. (C) 1 997 Elsevier Science Ltd.