Peripheral blood progenitor cell grafts contain high levels of platelet-secreted mediators.
BACKGROUND
The cytokine network in peripheral blood progenitor cell (PBPC) grafts may affect hematopoietic reconstitution or the risk of postransplant relapse of malignant disorders through effects on normal progenitor cells or contaminating malignant cells. Whether thrombopoietin (TPO), SCF, and platelet-secreted mediators are parts of this network was investigated.


METHODS
Peripheral blood and PBPC plasma samples were collected consecutively from patients with malignant disorders who underwent PBPC harvest. Blood samples were collected immediately before and after apheresis. Patients underwent mobilization by chemotherapy plus G-CSF, except for one patient who received only G-CSF. Plasma levels were also determined for healthy controls.


RESULTS
PBPC grafts had greater levels of platelet-secreted platelet factor 4 (PF4), beta-thromboglobulin, and platelet-derived growth factor isoform AB, as compared with venous levels in patients and controls. Although platelet and PF4 levels in autografts were significantly correlated, the graft:blood ratio was higher for PF4 than for platelets. In both the patients' blood and the autografts, TPO levels were increased from the levels in normal controls. Blood and graft levels of SCF were within the normal range.


CONCLUSIONS
The cytokine network of PBPC autografts includes increased levels of TPO and several platelet-derived mediators.
Foss
B
B
Institute of Medicine, University of Bergen, and the Blood Bank, Haukeland University Hospital, Bergen, Norway.
Abrahamsen
J F
JF
Bruserud
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D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000628:therapy*; D019007:P-Selectin / Q000097:blood; D010978:Platelet Factor 4 / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D012016:Reference Values; D019089:Stem Cell Factor / Q000097:blood / Q000378:metabolism; D013926:Thrombopoietin / Q000097:blood / Q000378:metabolism; D014182:Transplantation, Autologous; D014680:Veins
D019007:P-Selectin; D010982:Platelet-Derived Growth Factor; D019089:Stem Cell Factor; C095477:platelet-derived growth factor AB; D010978:Platelet Factor 4; D013926:Thrombopoietin