Apoptotic effects of heparin on lymphoblasts, neutrophils, and mononuclearcells: Results of a preliminary in vitro study

In this study the apoptotic effects of heparin on lymphoblasts, neutrophils , and mononuclear cells were evaluated by flow cytometry for detection of s ub G(1) peak, in vitro. Ten children with acute lymphoblastic leukemia (ALL ) at diagnosis (Group I), six children with ALL at relapse (Group II), and 10 healthy children (controls) were included in this study. Lymphoblasts in ALL patients, and neutrophils and mononuclear cells in controls, were incu bated in increasing heparin concentrations (0, 5, 10, 20 U/ml), Flow cytome tric analyses were performed at 0, 1, and 2 hours of incubation in heparin for determination of the apoptotic effects of heparin. In Group I apoptosis was detected in all different levels of heparin concentration except 0 U/m l at 0, 1, and 2 hours, The apoptotic effects of heparin on blast cells pea ked at the first hour in 5-, 10-, and 20-U/ml heparin concentrations (p < 0 .0001), In Group II similar findings were observed only at zero hour and ap optosis was higher than those in Group I except in 5-U/ml heparin concentra tion (p < 0.001). Apoptosis was found to increase with heparin levels in bo th groups (p < 0.02). In the control group, apoptosis was detected only at the 20-U/ml heparin concentration and only at the first and second hours, L ymphoblasts are more sensitive to apoptotic effects of heparin than either neutrophils and mononuclear cells (p < 0.004). It can be suggested that low -dose heparin may cause significant apoptosis of lymphoblasts while inducin g no apoptosis on neutrophils and mononuclear cells. The findings of this p reliminary study indicate that further and more comprehensive research on t he apoptotic effect of heparin on lymphoblasts should be done. Am. J, Hemat ol, 61:90-93, 1999, (C) 1999 Wiley-Liss, Inc.