A STUDY ON MECHANISMS OF NEUTROPHIL APOPTOSIS IN RAT CARRAGEENIN-INDUCED PLEURISY

粒细胞凋亡和随后的吞噬细胞清除对炎症的解决至关重要。然而，没有研究解决如何在炎症部位进行。采用TUNEL法、吖啶橙染色法和电泳DNA阶梯图检测大鼠角叉菜胶性胸膜炎中性粒细胞凋亡及单核白细胞摄食后的时间过程。注射角叉菜胶后3-5小时中性粒细胞开始积累，然后保持平稳状态至24小时。中性粒细胞在第1天和第3天急剧下降。单核白细胞在5小时开始积累，并在第2天达到高峰。tunel阳性体和吖啶橙阳性体分别在24小时和9小时在单核白细胞的细胞质中首次检测到。两种方法均表明含有片段DNA的单核白细胞在第1天和第2天迅速增加，并在第3天达到峰值。从5小时开始观察中性粒细胞DNA的特征性阶梯型。此外，在注射角叉菜胶9小时后，在渗出的白细胞中可以检测到一种凋亡相关蛋白Bad。这些结果表明，中性粒细胞在炎症部位开始积聚后就开始发生凋亡。因此，进化和消退过程可能在急性炎症中同时进行。副胸腺淋巴结随着炎症的进展而增大。肿大淋巴结内大量中性粒细胞和单核白细胞增多。这些细胞表达诱导型一氧化氮合酶。此外，在肿大的淋巴结中具有树突状突起的细胞表达环氧化酶-2。这些结果提示部分中性粒细胞转移到邻近的引流淋巴结。

Granulocyte apoptosis and subsequent clearance by phagocytes is critical for the resolution of inflammation. However, no studies have addressed how the resolution proceed in the inflammatory site. We studied the time course of neutrophil apoptosis and the following ingestion by mononuclear leukocytes in rat carrageenin-induced pleurisy, detecting DNA fragmentation by the TUNEL method, by acridine orange staining and from the DNA ladder pattern on electrophoresis. Neutrophil accumulation started 3-5 hrs after carrageenin injection, then maintained a plateau until 24 hr. Neutrophils decreased steeply between days 1 and 3. Mononuclear leukocytes started to accumulate at 5 hr, and reached a peak at day 2. TUNEL-positive bodies and acridine orange-positive bodies first became detectable in the cytoplasm of the mononuclear leukocytes from 24 hr and 9 hr, respectively. Both methods indicated that mononuclear leukocytes containing fragmented DNA increased rapidly on days 1 and 2, and reached a peak at day 3. The characteristic ladder pattern of neutrophil DNA was observed from 5 hr. Furthermore, an apoptosis related protein, Bad, became detectable in the exudate leukocytes from 9 hr after carrageenin injection. These results indicate that neutrophils start to undergo apoptosis just after the beginning of their accumulation in the inflammation site. Thus, evolution and resolution processes may proceed concurrently in acute inflammation.Parathymic lymph nodes enlarged with progression of inflammation. A large number of neutrophils and mononuclear leukocytes increasingly appeared in the enlarged lymph nodes. These cells expressed inducible nitric oxide synthase. In addition, cells possessing dendritic processes in the enlarged lymph nodes expressed cyclooxygenase-2. These results suggest that a part of neutrophils transmigrate into adjacent draining lymph nodes.