CD41+and CD42+hematopoietic progenitor cells may predict platelet engraftment after allogeneic peripheral blood stem cell transplantation

The objective of this study was to quantify subpopulations of CD34+ cells s uch as CD41+ and CD42+ cells that might represent megakaryocyte (MK) precur sors in peripheral blood stem cell (PBSC) collections of normal, recombinan t human granulocyte-colony stimulating factor (rhG-CSF) primed donors and t o determine whether there is a statistical association between the dose inf used megakaryocytic precursors and the time course of the platelet recovery following an allogeneic PBSC transplantation. Twenty-six patients with var ious hematologic malignancies transplanted from their HLA identical sibling s between July 1997 and December 1999 were used. All patients except one wi th severe aplastic anemia who had cyclophosphamide (CY) alone received busu lfan-CY as preparative regimen and cyclosporine-methotrexate for GVHD proph ylaxis. Normal healthy donors were given rhG-CSF 10 mug/kg/day subcutaneous ly twice daily and PBSCs were collected on days 5 and 6. The median number of infused CD34+, CD41+ and CD42+ cells were 6.61 x 10(6)/kg (range 1.47-21 .41), 54.85 x 10(4)/kg (5.38-204.19), and 49.86 x 10(4)/kg (6.82-430.10), r espectively. Median days of ANC 0.5 x 10(9)/L and platelet 20 x 10(9)/L wer e 11.5 (range 9-15) and 13 (8-33), respectively. In this study, the number of CD41+ and CD42+ cells infused much better correlated than the number of CD34+ cells infused with the time to platelet recovery of 20 x 10(9)/L in 2 6 patients receiving an allogeneic match sibling PBSC transplantation (r = -0.727 and P < 0.001 for CD41+ cells, r = -0.806 and P < 0.001 for CD42+ ce lls, r = -0.336 and P > 0.05 for CD34+ cells). There was an inverse correla tion between the number of infused CD41+ and CD42+ cells and duration of pl atelet engraftment. Therefore, as the number of CD41+ and CD42+ cells incre ased, duration of platelet engraftment (time to reach platelet count of gre ater than or equal to 20 x 10(9)/L) shortened significantly. Based on this data we may conclude that flow cytometric measurement of CD41+ and CD42+ pr ogenitor cells may provide an accurate indication of platelet reconstitutiv e capacity of the allogeneic PBSC transplant. J. Clin. Apheresis. 16:67-73, 2001. (C) 2001 Wiley-Liss, Inc.