Serum-soluble c-kit levels during mobilization of peripheral blood stem cells correlate with stem cell yield

c-Kit is expressed in hematopoietic stem cells and plays an important role in hematopoiesis. In 16 patients with malignancies, serum-soluble c-Kit lev els and the expressions of c-KIT messenger RNA (mRNA) and protein in periph eral blood mononuclear cells were analyzed serially during 26 courses of pe ripheral blood stem cell (PBSC) mobilization after granulocyte colony-stimu lating factor administration following chemotherapy for PBSC harvest. Serum -soluble c-Kit levels were significantly lower in patients than in controls (179.7 +/- 17.7 arbitrary units [AU]/mL versus 274.5 +/- 18.9 AU/mL; P < . 001), decreasing after chemotherapy (167.7 +/- 18.2 AU/mL), increasing from day 14, and peaking at day 19 (193.3 +/- 16.4 AU/mL). The numbers of both c-Kit(+) cells and CD34(+) cells and granulocyte-macrophage colony-forming units in peripheral blood peaked at day 17, following the peak of the expre ssion of c-KIT mRNA. Serum-soluble c-Kit levels showed a significant positi ve correlation with the numbers of CD34+ cells in both peripheral blood and leukapheresis products (r = 0.553, P < .01, and r = 0.640, P < .001, respe ctively) and changed at higher levels in patients with large numbers of PBS Cs versus patients with small numbers of PBSCs (P < .05). Serum-soluble c-K it may reflect the capacity for hematopoiesis after chemotherapy and may be useful in predicting the number of PBSCs that can be mobilized and harvest ed after mobilization, as well as for monitoring the timing for PBSC harves t. Int J Hematol. 2000;72:186-193. (C) 2000 The Japanese Society of Hematol ogy.