Human thymic stromal cell irradiation reduces intra-thymic T cell precursor proliferation: evidence for a soluble mediator.
OBJECTIVE
To investigate the effects of ionizing radiations on human thymic stromal cells and the consequences of stromal cell irradiation on T cell precursor proliferation.


METHODS
An in vitro model of thymic stromal cell culture was used. These cultures are able to support early CD7high T cell precursor proliferation and differentiation, mainly towards a CD3+TcRgamma+CD8+ pathway, in the presence of interleukin-7 and stem cell factor. Thymic stromal cell cultures were exposed to 10 Gy 60Co gamma-rays, 24 h before the seeding of CD7high T cell precursors.


RESULTS
Irradiation of thymic stromal cells induced a reduction in CD7high T cell precursors, without modifying their differentiation. This effect was reproduced by the addition of supernatants from irradiated stromal cell cultures in sham-irradiated cultures.


CONCLUSIONS
These results suggest that gamma-irradiation induces modifications in the production of soluble factors by thymic stromal cells, which in turn modify their ability to support T cell precursor proliferation. To the authors' knowledge this is the first direct demonstration that gamma-irradiation modifies the supportive function of thymic stromal cells.
Bertho
J M
JM
Section Autonome de Radiobiologie Appliquée à la Médecine, Institut de Protection et de Sûreté Nucléaire, Fontenay-aux-Roses, France. jean-marc.bertho@ipsn.fr
Gourmelon
P
P
D019011:Antigens, CD7 / Q000032:analysis; D002452:Cell Count; D002454:Cell Differentiation; D002455:Cell Division; D002470:Cell Survival; D002478:Cells, Cultured; D003470:Culture Media; D005720:Gamma Rays; D006412:Hematopoietic Stem Cells / Q000528:radiation effects*; D006801:Humans; D017154:Stromal Cells / Q000276:immunology / Q000528:radiation effects*; D013601:T-Lymphocytes / Q000528:radiation effects*; D013950:Thymus Gland / Q000528:radiation effects*
D019011:Antigens, CD7; D003470:Culture Media