[CDw90 (Thy-1) expression on CD34 positive cells in peripheral blood stem cell harvest]

In this study, we investigated CDw90 (Thy-1) expression in CD34+ cells and hematopoietic colony-forming ability in purified CD34+ Thy-1+ and CD34+ Thy-1 fractions in the peripheral blood at the PBSCH. The high proliferative potential colony-forming cells (HPP-CFC), which are considered to be more primitive hematopoietic stem cells, were found more frequently in the purified CD34+ Thy-1+ fraction than in the purified CD34+ Thy-1- fraction. Thus, it is useful to decide the optimal time of PBSCH to measure the CD34+ Thy-1+ cells as well as CD34+ cells in the peripheral blood by flow-cytometry. In CD34+ acute myeloblastic leukemia (AML) cells, the co-expression rate of CD34 and Thy-1 was negative, suggesting that it may be possible to estimate the contamination of CD34+ AML cells by the Thy-1 expression rate in CD34+ cells at PBSCH.