Kinetics of CFU-Mk after automated plateletpheresis

Background and Objectives Platelet count, thrombopoetin (TPO) level and the compartment of megakaryocyte progenitor cells (CFU-Mk) are major determina nts in the regulation of thrombopoiesis. The aim of this study was to inves tigate the potential changes in the compartment of CFU-Mk and their correla tion with serum TPO levels and platelet count after plateletpheresis. Materials and methods Twelve healthy individuals were randomly assigned to undergo single-donor plateletpheresis. A collagen-based in vitro culture sy stem was used to determine the number of peripheral blood (PB) CFU-Mk befor e and after donation and on days 1, 4 and 7 thereafter. TPO levels were mea sured by a specific enzyme-linked immunosorbent assay and whole blood count s were performed using an automated cell counter. Results The pre-apheresis platelet count (mean SEM: 276 +/- 13 x 10(9)/l) d ecreased after plateletpheresis to a nadir of 194 +/- 8 x 10(9)/l (P < 0.00 1), showed a gradual increase on days 1 and 4, and reached pre-apheresis va lues by day 7 (280 +/- 11). The serum TPO levels were found to be significa ntly increased on days 1 and 7 as compared to baseline levels (baseline val ue 103.3 +/- 18.5 pg/ml versus day-1 value 135.8 +/- 25.8 pg/ml and day-7 v alue 132 +/- 30.19 pg/ml; P < 0.03 and P < 0.03, respectively). The numbers of CFU-Mk in PB were significantly elevated on day 4 only (125 +/- 21 colo nies/ml of PB versus pre-apheresis values of 68 +/- 18 colonies/ml. of PB, P < 0.005). Conclusions These findings suggest that platelet loss during plateletpheres is affects thrombopoiesis at the progenitor cell level, probably through al terations in TPO plasma concentrations.