Flow cytometric estimation of the plasma membrane diversity of bone marrow cells in mice treated with WR-2721 and cyclophosphamide.

The effects of S-2-/3-aminopropylamino/ethyl phosphorothioic acid (WR-2721, Amifostine) and cyclophosphamide (CP) on the cell surface exposure of phosphatidylserine (PS) and the plasma membrane impairment of bone marrow cells were assessed by flow cytometry assay with fluoresceinated annexin V (annexin V - FITC) and propidium iodide (PI). During the 96 h-period after treatment of adult male Swiss mice with WR-2721 (400 mg/kg b.wt.) and CP (200 mg/kg b.wt.), bone marrow cells expressing PS on the outer leaflet of the plasma membrane, which bound annexin V, and cells with a compromised cell membrane, which allowed PI to bind to the cellular DNA, were analysed. Temporary changes in the frequency of early apoptotic cells (annexin V - FITC positive/PI negative), late apoptotic and necrotic cells (annexin V - FITC positive/PI positive), and the number of live cells (annexin V - FITC negative/PI negative), were dependent on the drug(s) given. Application of CP distinctly triggered apoptotic and necrotic cell death, and WR-2721 pre-treatment of mice affected cell death induced by CP, causing reduction of the number of apoptotic and necrotic cells. The chemoprotective action of WR-2721 against PS externalisation and the plasma membrane impairment of normal bone marrow cells was shown.