title: Pleomorphic Structures in Human Blood Are Red Blood Cell-Derived Microparticles, Not Bacteria.
abstract: BACKGROUND
  Red blood cell (RBC) transfusions are a common, life-saving therapy for many patients, but they have also been associated with poor clinical outcomes. We identified unusual, pleomorphic structures in human RBC transfusion units by negative-stain electron microscopy that appeared identical to those previously reported to be bacteria in healthy human blood samples. The presence of viable, replicating bacteria in stored blood could explain poor outcomes in transfusion recipients and have major implications for transfusion medicine. Here, we investigated the possibility that these structures were bacteria.
  
  
  RESULTS
  Flow cytometry, miRNA analysis, protein analysis, and additional electron microscopy studies strongly indicated that the pleomorphic structures in the supernatant of stored RBCs were RBC-derived microparticles (RMPs). Bacterial 16S rDNA PCR amplified from these samples were sequenced and was found to be highly similar to species that are known to commonly contaminate laboratory reagents.
  
  
  CONCLUSIONS
  These studies suggest that pleomorphic structures identified in human blood are RMPs and not bacteria, and they provide an example in which laboratory contaminants may can mislead investigators.
authors.affiliation: Division of Cardiology, Department of Medicine, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Mitchell
authors.affiliation: Division of Cardiology, Department of Medicine, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Warren D
authors.initials: WD
authors.lastname: Gray
authors.affiliation: Division of Infectious Disease, Department of Medicine, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Max
authors.initials: M
authors.lastname: Schroeder
authors.affiliation: Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Hong
authors.initials: H
authors.lastname: Yi
authors.affiliation: Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Jeannette V
authors.initials: JV
authors.lastname: Taylor
authors.affiliation: Division of Infectious Disease, Department of Pediatrics, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Dillard
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America.
authors.forename: Zunlong
authors.initials: Z
authors.lastname: Ke
authors.affiliation: Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, Georgia, United States of America.|Division of Infectious Disease, Department of Pediatrics, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Wright
authors.affiliation: Division of Infectious Disease, Department of Medicine, Emory University, Atlanta, Georgia, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Stephens
authors.affiliation: Center for Transfusion and Cellular Therapy, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia, United States of America.
authors.forename: John D
authors.initials: JD
authors.lastname: Roback
authors.affiliation: Division of Cardiology, Department of Medicine, Emory University, Atlanta, Georgia, United States of America.|Section of Cardiology, Atlanta VA Medical Center, Decatur, Georgia, United States of America.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Searles
mesh_terms: D001419:Bacteria / Q000166:cytology*; D001798:Blood Proteins / Q000378:metabolism; D048430:Cell Shape; D048429:Cell Size; D055252:Cell-Derived Microparticles / Q000382:microbiology; D004269:DNA, Bacterial / Q000378:metabolism; D004912:Erythrocytes / Q000166:cytology* / Q000382:microbiology / Q000648:ultrastructure; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D008854:Microscopy, Electron; D013997:Time Factors
chemical_list: D001798:Blood Proteins; D004269:DNA, Bacterial; D035683:MicroRNAs