Variations in the content of CD34(+) cells in the peripheral blood of cancer patients receiving out-patient chemotherapy

Background The routine measurement of CD34(+) cells in non-mobilized peripheral blood using flow cytometry, has been limited by the technical difficulty of measu ring the absolute numbers of rare populations of cells. Methods We studied the numbers of CD34(+) cells in the peripheral blood of 55 norma l volunteers and 476 cancer patients receiving chemotherapy, in a universit y out-patient hematology/oncology clinic. Blood samples were stained with M Abs to CD34, CD45 and a DNA-specific dye, mixed with a defined number of fl uorescent True-Count beads and analyzed by flow cytometry, using an automat ed aquisition 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/m u L, was stable among normal volunteers and patients receiving chemotherapy for prostate or breast cancer. In contrast, the CD34(+) cell count among p atients receiving dose-intensive weekly chemotherapy for the treatment of H odgkin's disease or non-Hodgkin's lymphoma varied between 1 cell/mu L to > 300 CD34(+) cells/mu L 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 sin gle platform program in an out-patient setting. The availability of an auto mated data acquisition and analysis program could facilitate standardizatio n of counting CD34(+) cells in clinical samples analyzed at different labor atory sites.