title: Shifts in bone marrow cell phenotypes caused by spaceflight.
abstract: Bone marrow cells were isolated from the humeri of C57BL/6 mice after a 13-day flight on the space shuttle Space Transportation System (STS)-118 to determine how spaceflight affects differentiation of cells in the granulocytic lineage. We used flow cytometry to assess the expression of molecules that define the maturation/activation state of cells in the granulocytic lineage on three bone marrow cell subpopulations. These molecules included Ly6C, CD11b, CD31 (platelet endothelial cell adhesion molecule-1), Ly6G (Gr-1), F4/80, CD44, and c-Fos. The three subpopulations were small agranular cells [region (R)1], larger granular cells (R2), which were mostly neutrophils, and very large, very granular cells (R3), which had properties of macrophages. Although there were no composite phenotypic differences between total bone marrow cells isolated from spaceflight and ground-control mice, there were subpopulation differences in Ly6C (R1 and R3), CD11b (R2), CD31 (R1, R2, and R3), Ly6G (R3), F4/80 (R3), CD44(high) (R3), and c-Fos (R1, R2, and R3). In particular, the elevation of CD11b in the R2 subpopulation suggests neutrophil activation in response to landing. In addition, decreases in Ly6C, c-Fos, CD44(high), and Ly6G and an increase in F4/80 suggest that the cells in the bone marrow R3 subpopulation of spaceflight mice were more differentiated compared with ground-control mice. The presence of more differentiated cells may not pose an immediate risk to immune resistance. However, the reduction in less differentiated cells may forebode future consequences for macrophage production and host defenses. This is of particular importance to considerations of future long-term spaceflights.
authors.affiliation: Kansas State University, Manhattan, Kansas, USA.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Ortega
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pecaut
authors.forename: Daila S
authors.initials: DS
authors.lastname: Gridley
authors.forename: Louis S
authors.initials: LS
authors.lastname: Stodieck
authors.forename: Virginia
authors.initials: V
authors.lastname: Ferguson
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Chapes
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D000950:Antigens, Ly / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D039481:CD11b Antigen / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation; D019070:Cell Lineage; D005260:Female; D005434:Flow Cytometry; D006098:Granulocytes / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D018960:Hyaluronan Receptors / Q000378:metabolism; D016130:Immunophenotyping; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D013026:Space Flight; D014893:Weightlessness
chemical_list: D000943:Antigens, Differentiation; D000950:Antigens, Ly; D015415:Biomarkers; D039481:CD11b Antigen; C476399:Cd44 protein, mouse; D018960:Hyaluronan Receptors; C494192:Ly-6C antigen, mouse; C480309:Ly6G antigen, mouse; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D016760:Proto-Oncogene Proteins c-fos; C036763:monocyte-macrophage differentiation antigen