Thrombopoietin serum levels at the start of mobilization, collection, and transfusion of autologous peripheral blood stem cells.

Thrombopoietin (TPO) serum levels in 14 patients (9 male and 5 female, mean age 36 years, range 16 to 55 years) with breast cancer (n = 5), testicular cancer (n = 7), or lymphoma (n = 2), undergoing high dose chemotherapy with peripheral blood stem cell (PBSC) transplantation, were evaluated at the first day of the mobilization chemotherapy (1), at the day of the first apheresis (2), and at the day of stem cell transfusion (3). All patients have been pretreated (one to four regimens) and received chemotherapy and granulocyte colony stimulating factor (G-CSF) or granulocyte-macrophage colony stimulating factor (GM-CSF) both at 5 microg/kg body weight (bw). for stem cell mobilization. TPO was measured with a human TPO immunoassay. Mean TPO serum levels were: (1) 274+/-248.8 pg/ml (range 0 to 953 pg/ml), (2) 518+/-399.1 pg/ml (range 118 to 1,283 pg/ml), and (3) 556+/-506.4 pg/ml (range 147 to 1,570 pg/ml). The CD34+ cell concentration in the peripheral blood at the time of apheresis was 65+/-48.2/microl (7 to 148/microl), and the number of transfused CD34+ cells was 3.0+/-1.0x10(6)/kg bw (1.7 to 5.5x10(6)/kg bw). TPO levels showed some weak inverse correlation (r = -0.64) with the platelet counts at the day of the first apheresis that increased to -0.70 if a semilog correlation was done (plt[log] vs. TPO). The number of platelet transfusions after HDCT correlated to some degree (r = 0.61) with the TPO serum level at the day of PBSC transfusion. There was no correlation between any TPO serum level and the CD34+ cell concentration in the peripheral blood or neutrophil and platelet engraftment. We conclude from this study that TPO serum levels do not seem to correlate with the CD34+ cell concentration in the peripheral blood and the time to engraftment, although there was some weak correlation with the number of platelet transfusions.