X射线全身照射对免疫细胞共刺激分子表达的影响

目的：探讨低剂量电离辐射对免疫细胞表面分子的影响，方法：用流式细胞术FITC－CD28／PE－CTLA－4双染染法观察了小鼠胸腺和脾细胞的CD28和CTLA－4表达变化，用免疫细胞化学（ABC）法观察了小鼠腹腔巨噬细胞B7－1和B7－2的表达变化。结果：低剂量电离辐射和较高剂量电离辐射均能增强腹腔巨噬细胞B7分子的表达；同时发现，低量电离辐射显著增强胸腺和脾细胞CD28的表达，而CTLA－4的表达降低，脾细胞较胸腺细胞更明显。较高剂量电离辐射显著增强胸腺和脾细胞CTLA－4的表达，同时抑制两种细胞CD28的表达，以脾细胞为更显著，结论：共刺激分子CD28和B7的表达上调可能是低剂量电离辐射免疫兴奋效应机理中的重要因素。

Effect of whole-body X-irradiation on the expression of costimulatory molecules on immune cells

Objective\ To study the effect of ionizing radiation on costimulatory molecules on immune cells. Methods\ Flow cytometry (FCM) was used to detect the changes in the expression of CD28/CTLA\|4 of thymocytes and splenocytes after whole\|body irradiation (WBI) with different doses of X\|rays.Immunohistochemistry (IHC,ABC method) was used to detect the changes in the expression of B7 1 and B7 2 on peritoneal ma crophages after WBI with different doses of X\|rays. Results\ The results showed that 0\^075 Gy X rays caused significant up regulation of CD28 on both thymocytes and splenocytes and down\|regulation of CTLA\|4 expression,which was more significant on the splenocytes.After 2 Gy irradiation the expression of CTLA\|4 on both thymocytes and splenocytes was significantly up\|regulated with down\|regulation of CD28 expression,which was more significant on the splenocytes.The dose\|effect studies showed that there was no change in the expression of CTLA\|4 on the thymocytes 72 h after LDR,while 2 and 4 Gy caused apparent increase in the expression of CTLA\|4( P <0\^05, P <0\^01).For splenocytes,LDR caused no changes in the expression of CTLA\|4 4 h after irradiation,while higher doses could increase the expression of CTLA\|4 significantly ( P <0\^05, P <0\^01).The expression of B7 1 and B7 2 on peritoneal macrophages increased after both 0\^075 Gy and 2 Gy X\|rays.The increase in B7 2 expression preceded that of B7\|1 expression after 0\^075 Gy and lasted longer than after 2 Gy irradiation. Conclusion\ Up\|regulation of expression of costimulatory molecules CD28 and B7 after whole\|body X\|irradiation may be an important factor involved in the enhancing effect of low dose radiation on immunity.