Hemopoietic stem and precursor cell analysis in umbilical cord blood usingthe Sysmex SE-9000 IMI channel

Circulating hematopoietic progenitor cells (HPCs) are routinely measured by flow cytometry using CD34 expression. As an alternative, the "immature inf ormation" (IMI) channel measurement of the automated hematology analyzer Sy smex SE machines was developed. We tested the IMI channel HPC method with u mbilical cord blood specimens. The IMI-HPCs were compared with CD34 counts and numbers of colony-forming units (CFUs), The IMI-HPC data were reproduci ble and dilution experiments yielded a log-linear relationship, The mean pe rcentage of CD34(+) cells in 50 umbilical cords was 0.43 versus 0.11 of HPC s in the IMI channel (correlation coefficient r = 0.67), Absolute numbers y ielded 96.79 x 10(6)/L CD34(+) 33.17 x 10(6)/L IMI-HPC, and 35.04 x 10(6)/L CFU-HPC. Receiver operating characteristics curves were made at various cu toff levels for CD34(+) cells to visualize sensitivity and specificity prof iles. With median values of 13.56 x 10(6)/L for IMI-HPC and 20 x 10(6)/L fo r CD34(+) as cutoff points (the levels used in the laboratory to start stem cell pheresis), the percentage of false-negative observations was 70.4%, T o exclude the influence of storage time, tests were repeated until 72 h aft er umbilical cord collection. Total white blood cell count decreased in mos t cases, whereas absolute number of IMI-HPC tended to increase in time. In conclusion, if HPC measurements in the IMI channel are used to monitor circ ulating stem cells during mobilization, one has to be aware of a very low c orrelation between these results and those of other methods such as CD34(+) analysis and colony growth. False-negative results do occur, but if events are seen in the IMI channel, this simple monitoring technique is useful to predict the presence of circulating stem cells. (C) 2001 Wiley-Liss, Inc.