Flow cytometry using annexin V can detect early apoptosis in peripheral blood stem cell harvests from patients with...

Quantifying progenitor cells in peripheral blood stem cell (PBSC) harvests by flow cytometric enumeration of CD34+ cells does not account for cell viability. Cell membrane asymmetry in early apoptosis exposes phosphatidylserine on the cell surface. This can be detected by staining with annexin V FITC. Apoptosis in 30 autologous PBSC harvests mobilised by cyclophosphamide + G-CSF or standard chemotherapy + G-CSF was analysed immediately after collection by dual-colour flow cytometry with CD34 PE and annexin V FITC. Harvests contained a median of 3.4 x 10(6)/kg (range 0.3-91.8) CD34+ cells. Of these 87.6% (range 30-96.5) were annexin V-. In 10% of harvests more than 50% of CD34+ cells were apoptotic. Differences in PBSC mobilisation or collection could not explain the variation in annexin V binding. Cyclophosphamide + G-CSF significantly increased the yield of CD34+ cells but did not increase apoptosis. Comparison of consecutive harvests showed no difference in the numbers of CD34+ cells collected but found a significant decrease in apoptotic CD34+ cells through multiple collections. Analysis of annexin V binding in PBSC harvests is a simple flow cytometry technique which gives additional information on the status of CD34+ progenitor cells.