title: Measurement of the absolute immature platelet number reflects marrow production and is not impacted by platelet transfusion.
abstract: BACKGROUND
  The ability to distinguish increased platelet (PLT) destruction from PLT hypoproduction is important in the care of patients with marrow failure syndromes and patients receiving high-dose chemotherapy. The measurement of immature circulating PLTs based on RNA content using an automated counter is now feasible. This study evaluated the impact of recent PLT transfusion on measurement of immature PLT variables.
  
  
  METHODS
  The immature PLT fraction (IPF) and absolute immature PLT number (AIPN) were measured using a hematology analyzer before and after PLT transfusion in nine transfusion-dependent patients with marrow failure secondary to aplastic anemia, myelodysplasia, or transplantation conditioning. IPF and AIPN were also measured serially over 5 days of storage in three plateletpheresis components collected from normal donors.
  
  
  RESULTS
  PLT transfusion did not significantly change the mean AIPN in transfused patients. In contrast, IPF decreased significantly from 6.6 ± 4.6% on Day -1 to 2.3 ± 1.4% on Day 0 before returning to 4.3 ± 2.3% on Day +1. In the PLT component, AIPN and IPF% increased significantly over 5 days of storage, most likely due to an artifact of the staining and detection process for stored PLTs, no longer detected in vivo once the PLTs were transfused.
  
  
  CONCLUSIONS
  PLT transfusion decreases the IPF due to the resultant increase in circulating PLT count. However, PLT transfusion does not change the circulating AIPN, validating this assay as a reflection of ongoing PLT production by the marrow in various clinical settings, regardless of proximity to PLT transfusion.
authors.affiliation: Hematology Branch, National Heart, Lung, and BloodInstitute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Taha
authors.initials: T
authors.lastname: Bat
authors.forename: Susan F
authors.initials: SF
authors.lastname: Leitman
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Calvo
authors.forename: Donna
authors.initials: D
authors.lastname: Chauvet
authors.forename: Cynthia E
authors.initials: CE
authors.lastname: Dunbar
mesh_terms: D000741:Anemia, Aplastic / Q000097:blood / Q000503:physiopathology / Q000628:therapy; D001792:Blood Platelets / Q000166:cytology*; D001853:Bone Marrow / Q000502:physiology*; D001855:Bone Marrow Diseases; D000080983:Bone Marrow Failure Disorders; D018380:Hematopoietic Stem Cell Transplantation; D006457:Hemoglobinuria, Paroxysmal / Q000097:blood* / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D009190:Myelodysplastic Syndromes / Q000097:blood / Q000503:physiopathology / Q000628:therapy; D010976:Platelet Count / Q000379:methods; D017713:Platelet Transfusion; D010983:Plateletpheresis; D019172:Transplantation Conditioning