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目的探讨糖皮质激素诱导小鼠胸腺细胞死亡的形态学改变。方法4~6周龄雌性BALB/C小鼠腹腔注射地塞米松,采用末端转移酶介导的dUTP缺口末端标记(TUNEL)法检测DNA单链或双链的裂解,TUNEL和酸性磷酸酶(ACP)双重染色法进行酸性磷酸酶的检测,观察细胞凋亡后吞噬细胞的活动,透射电子显微镜检测凋亡细胞和吞噬细胞的超微结构。结果光镜观察地塞米松组,TUNEL阳性细胞较多并且分散在皮质各处,凋亡指数为0.460±0.012;正常对照组TUNEL阳性细胞数目较少,凋亡指数为0.020±0.001,与地塞米松组比较,差异有显著性(P<0.05)。TUNEL和酸性磷酸酶双重染色法显示,所有TUNEL阳性胸腺细胞均被ACP阳性细胞吞噬。透射电子显微镜观察发现,大部分凋亡细胞均被吞噬细胞所吞噬,少量未被吞噬的胸腺细胞表现出大范围的染色质浓集,这些少量未被吞噬的胸腺细胞显然是死细胞。结论典型的细胞凋亡的特点是DNA裂解,但这不是糖皮质激素诱导胸腺细胞死亡的主要方式,死亡的胸腺细胞均是被ACP阳性细胞所吞噬;糖皮质激素对胸腺细胞的首要影响是可诱导无DNA裂解的细胞固缩。
Objective To investigate the morphological changes of mouse thymocytes induced by glucocorticoids. Methods Female BALB / C mice (4 to 6 weeks old) were injected intraperitoneally with dexamethasone. The single strand or double strand DNA cleavage, TUNEL and acid phosphatase (ACP) were detected by terminal transferase mediated dUTP nick end labeling (TUNEL) ) Double staining method for the detection of acid phosphatase activity of apoptotic phagocytes was observed after transmission electron microscopy apoptotic cells and phagocytic ultrastructure. Results In the dexamethasone group, TUNEL-positive cells were more dispersed in the cortex and the apoptotic index was 0.460 ± 0.012. The number of TUNEL-positive cells in the normal control group was less, the apoptotic index was 0.020 ± 0.001, The difference was significant (P <0.05). TUNEL and acid phosphatase double staining showed that all TUNEL positive thymocytes were phagocytosed by ACP positive cells. Transmission electron microscopy revealed that most of the apoptotic cells were phagocytosed by phagocytes, and a small amount of non-phagocytic thymocytes showed a wide range of chromatin condensation. These small amounts of undeveloped thymocytes were apparently dead cells. CONCLUSIONS Typical apoptotic cells are characterized by DNA cleavage, but this is not the predominant form of glucocorticoid-induced thymocyte death. Thymic cells that are dead are both phagocytized by ACP-positive cells; the primary effect of glucocorticoids on thymocytes is Cell shrinkage induced without DNA lysis.