Objective  This work aims to investigate the relationship between bcl-2 and VEGF antigen expression and the in situ apoptosis of hematopoietic cells in myelodysplastic syndrome(MDS), and to discuss the pathogenesis of MDS.

  Methods  Through bone marrow biopsy, the degree of bone marrow hyperplasia, morphological abnormity of hematopoietic cells, and histopathological change, called abnormal localization of immature precursor(ALIP) in light microscopy were observed.Immunohistochemistry was used to monitor the bcl-2 and VEGF antigen expressions.The in situ apoptosis of hematopoietic cells was detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) method.

  Results  Different degrees of hematopoietic abnormalities were found in all 13 cases.The two groups with refractory anemia(RA) and refractory anemia with excess of blasts(RAEB) had no significant differences.ALIP was detected in 6 cases, of which 3 were RA(3/8, 37.50%) and the other 3 were RAEB(3/5, 60.00%).Positive VEGF expression was observed in 9 cases, of which 6 were RA(6/8, 750%) and the other 3 were RAEB(3/5, 60.00%).Positive bcl-2 expression was found in 7 cases, including 4 with RA(4/8, 50.00%) and three with RAEB(3/5, 60%).All patients had positive TUNEL results.The patients with ALIP showed higher degrees of in situ apoptosis of hematopoietic cells.

  Conclusion  MDS patients have various degrees of abnormal apoptosis of hematopoietic cells.The TUNEL method is simple, practical, sensitive, convenient, and specific tool for detecting in situ cell apoptosis.However, the mechanisms in hematopoietic cell apoptosis and clonally malignant proliferation in MDS patients may differ greatly.