ABSTRACT
BACKGROUND: The routine measurement of CD34+ cells in non-mobilized peripheral blood, using flow cytometry, has been limited by the technical difficulty of measuring the absolute numbers of rare populations of cells. METHODS: We studied the numbers of CD34+ cells in the peripheral blood of 55 normal volunteers and 476 cancer patients receiving chemotherapy, in a university out-patient hematology/oncology clinic. Blood samples were stained with MAbs to CD34, CD45 and a DNA-specific dye, mixed with a defined number of fluorescent True-Count beads and analyzed by flow cytometry, using an automated acquisition and analysis program. RESULTS: The mean (+/- SD) CD34+ cell count among normal volunteers and previously untreated cancer patients were 1.4 +/- 1.4 and 1.8 +/- 2.8 CD34+ cells/microL, was stable among normal volunteers and patients receiving chemotherapy for prostate or breast cancer. In contrast, the CD34+ cell count among patients receiving dose-intensive weekly chemotherapy for the treatment of Hodgkin's disease or non-Hodgkin's lymphoma varied between 1 cell/microL to > 300 CD34+ cells/microL in a predictable and cyclic fashion. DISCUSSION: The study demonstrates that the routine measurement of the number of CD34+ cells in peripheral blood samples can be performed using an automated single platform program in an out-patient setting. The availability of an automated data acquisition and analysis program could facilitate standardization of counting CD34+ cells in clinical samples analyzed at different laboratory sites.
