The effect of ionizing radiation on intra-thymic T cell development was investigated using a fetal thymic organ culture (FTOC) method in vitro. When double-negative (DN) fetal (day 15) thymocytes were co-cultured with an irradiated (25 Gy) fetal (day 15) thymus in the absence of direct contact or mitogenic stimulation, the induction of TCRgammadelta+ T cells was observed. About 50% of the TCRgammadelta+ T cells developed after 4-day-co-culture with the irradiated fetal thymus, whereas only a few TCRgammadelta+ T cells developed after co-culture with the non-irradiated fetal thymus. About 50% of the TCRgammadelta+ T cells were @entity405 + cells with alphabeta heterodimeric chains. Cultured supernatants of the irradiated fetal thymi also induced the differentiation from DN thymocytes to @entity405 + TCRgammadelta+ T cells after 3-day-culture. To clarify the factor in the cultured supernatants, several neutralizing antibodies (Abs) were used. Only anti- @entity6977 -Ab inhibited the differentiation from DN thymocytes to @entity405 + TCRgammadelta+ T cells. RT-PCR revealed the increased expression of @entity6977 mRNA in the fetal thymus 24 hours after radiation. Electron microscope studies demonstrated proliferative epithelial cells in the irradiated fetal thymus. These findings strongly suggest that fetal thymic epithelial cells affected by irradiation proliferate and enhance the production of @entity6977 , which induces the differentiation of @entity405 + TCRgammadelta+ T cells from DN thymocytes.

Enhancement of XXXX following irradiation of fetal thymus.

@entity6977 :: ('3574', 'Gene') :: ['IL-7'] @entity405 :: ('925', 'Gene') :: ['CD8']
@entity6977 :: (3574,Gene) :: ['IL-7']
