用^3H—TdR释放法测定小鼠NK细胞的辐射敏感性

用~3H—TdR释放法测定C_(57)BL/6小鼠脾细胞对YAC-1细胞林的NK活性,首次将该法应用于研究NK细胞对γ线的辐射敏感性,得出如下结论:(1)小鼠整体照射后24h脾脏NK活性的D_(37)约为17Gy,D_0约为11Gy;在24～32Gy范围内仍保留着30%的NK活性,存活曲线为反“S”形,验证了NK细胞总体对辐射的相对耐受性。(2)脾细胞离体或整体照射1～2Gy后即刻NK活性均迅速下降,在2～24Gy内,离体和整体照射组的NK活性分别维持在40%～80%和50%,前者高于后者,说明NK细胞对离体照射比对整体照射更不敏感。(3)小鼠整体照射后24h,全脾细胞数在较小剂量(<4Gy)内急剧下降,然后随剂量增大变化平缓。可以推测NK活性的变化与脾细胞总数的改变有一定关系。(4)综合分析本实验结果,可以设想NK细胞本身可能存在着辐射敏感性不同的亚群。(5)用~3H—TdR释放法测定NK细胞的辐射敏感性,自然释放率低,重复性好,可靠易行。

Measurement of the radiosensitivity of splenic NK cells in mice by using ~3H-TdR releasing assay

The ~3H-TdR releasing assay was used for the first time by us in studying theradiosensifivity of splenic NK cells in gamma-irradiated C_(57)BL / 6 mice. It was found that: (1) 24hours after irradiation in vivo, the D_(37) and D_0 values of splenic NK activity were about 17Gyand 11Gy respectively; after 24-32Gy irradiation, 30% of the NK activity remained, confirmingthe relative radioresistance of NK cells, and the survival curve is in a reverse "S" - shape; (2) whenmeasured immediately after in vitro or in vivo irradiation, 1-2Gy induced sharp decrease of NKactivity, while 2-24Gy gave the survival fractions of 40%-80% and 50% for in vitro and in vivoradiation respectively. NK cells are more resistant to irradiation in vitro than in vivo; (3) 24 hours after irradiation in vivo, the total number of splenic cells decreased sharply at low doses (<4Gy)and slowly at higher doses, and it might have a close relationship to the change of NK activity; (4)there might exist subgroups of NK cells with different radiosensitivities; (5) with low spontaneousreleasing and high repeatability, ~3H-TdR releasing assay is a useful and reliable method for stud-ying NK activity and radiosensitivity of NK cells.