Studies on the organ-associated natural killer cells (pit cells)

本研究在电子显微镜下揭示了肝脏相关自然杀伤(NK)细胞是肝脏抵御肿瘤生长或转移防御系统的重要组成部分。肝脏相关NK细胞体内杀伤肿瘤细胞的超微结构研究(1)瘤体内注射的Yac-1肿瘤细胞被血窦内的NK细胞杀伤。提示NK细胞的颗粒和杆状囊泡在细胞溶解中可能起重要作用。NK细胞还可与相关的Kupffer细胞协同吞噬Yac-1细胞。这项研究首次显示了体内NK细胞溶解的直接证据。(2)在人原发性肝癌中，我们观察到NK细胞由于有纤维性包膜而未接近肿瘤细胞，或有NK细胞渗入瘤体内。体外细胞溶解过程中NK细胞细胞器的分布。(1)从脾或肝分离的NK细胞与Yac-1细胞共培养时，与肿瘤细胞接触并向肿瘤细胞延伸投射。NK细胞的细胞器向Yac-1细胞重定向，棒状囊泡沿微管排列，微管从中心粒延伸到接触区。这表明杆状核小泡在NK细胞溶解过程中起重要作用，它是NK细胞的特征。(Ii)我们现正进行有关NK细胞分解过程的摄影分析。

This study has revealed electron microscopically that liver-associated natural killer (NK) cells are the important constituent of the defense system of the liver against the tumor growth or metastasis.1. Ultrastructural study of in vivo cytolysis of tumor cells by liver-associated NK cells. (i) Intraportally injected Yac-1 tumor cells were cytolysed by NK cells inside the sinusoids. It was suggested that granules and rod-cored vesicles of NK cells would be important in the cytolysis. NK cells could also phagocytize Yac 1 cells in cooperation with associating Kupffer cells. This study is the first to show the direct evidence of in vivo NK cytolysis. (ii) In the human primary hepatoma, we observed that NK cells infiltrated into the tum or but they did not approach to the tumor cells due to the fibrous capsule.2. Distribution of cell organelles of NK cells during the in vitro cytolysis. (i) When NK cells which were isolated from the spleen or liver were co-cultured with Yac-1 cells, they contacted with and extended the projections toward the tumor cells. The cell organelles of NK cells were reoriented toward the Yac-1 cells, and the rod-cored vesicles were aligned along the microtubules which ran to the contact area from the centrioles. This suggests that rod-cored vesicles, highly characteristic to NK cells, are important in NK cytolysis. (ii) We are now developing the cinematographic analysis about the process of NK cytolysis.