Increased and decreased expression of CD69 and CD23, respectively, in gravity-stressed lymphocytes.
BACKGROUND
Recent studies have shown that gravity-changing stress modulates expression levels of cell surface molecules on human lymphocytes. However, previous in vitro microgravity studies have been performed with lymphocytes treated with mitogenic agents.


OBJECTIVE
The aim of the study was to test if exposure of cells to gravity-changing stress alone alters the expression levels of cell surface molecules. Specifically, we examined whether the expression of activation markers is altered after exposure of lymphocytes to combinations of microgravity and hypergravity.


METHODS
We used free-fall in parabolic flight for human subjects and a drop-shaft to expose peripheral blood mononuclear cells (PBMC) to gravity-changing stress. After such exposure, PBMC were isolated, and expression levels of CD69, CD23 and CD38 were estimated using three-color flow cytometry.


RESULTS
Increased percentages of CD69-positive cells were observed with PBMC from 3 of 4 volunteers who undertook 10 parabolic flights. Exposure of blood to gravity-changing stress in the drop-shaft increased both ratios of CD69-positive cells and levels of CD69 expression on T and B cells. In contrast, the percentages of CD23-positive B cells was decreased. However, gravity-changing stress was not always followed by significant alteration in CD38 expression.


CONCLUSIONS
Our findings suggest that CD69 and CD23 might be useful markers that are up- and down-regulated, respectively, after exposure of lymphocytes to gravity-changing stress.
Nomura
J
J
Department of Biochemistry, School of Medicine, Chiba University, Japan.
Arase
Y
Y
Sugita
T
T
Sugaya
S
S
Takahashi
S
S
Kita
K
K
Yamamori
H
H
Sekiya
S
S
Suzuki
N
N
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000328:Adult; D015703:Antigens, CD / Q000378:metabolism*; D000943:Antigens, Differentiation / Q000378:metabolism*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism*; D015415:Biomarkers; D005260:Female; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins; D009244:NAD+ Nucleosidase / Q000378:metabolism*; D017455:Receptors, IgE / Q000378:metabolism*; D013026:Space Flight; D018474:Weightlessness Simulation / Q000009:adverse effects*; D000099192:CD69 Antigens
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D015703:Antigens, CD; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D015415:Biomarkers; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D009244:NAD+ Nucleosidase; D017455:Receptors, IgE; D000099192:CD69 Antigens; C498154:CD38 protein, human