IDENTIFICATION AND CHARACTERIZATION OF MATERIALS SECRETED BY CLARA CELLS

细支气管克拉拉细胞的功能尚不清楚，尽管数量众多。 对许多物种的形态研究导致了这一假说 细胞是分泌的。这项研究的目的是 阐明Clara细胞的分泌性质，鉴定和鉴定 这些分泌物并确定它们的细胞外功能。我们有 开发了一个研究Clara细胞功能的模型系统和 利用从兔肺分离的细胞进行新陈代谢。克拉拉细胞是 用胰蛋白酶从肺中分散，提纯到90%以上 通过顺序地使用各种技术，包括离心式 淘洗、密度梯度离心法、差速贴壁法和 体外培养。分离的Clara细胞与 35S-蛋氨酸作用4小时导致许多细胞内的放射性标记 一些蛋白质被释放到孵育液中。 比较了Clara细胞蛋白质的生物合成和分泌。 与其他分离和纯化的合成和分泌的 肺细胞，包括肺泡巨噬细胞、II型细胞和基底细胞 细胞。标记的细胞蛋白和从细胞中释放的蛋白 用十二烷基硫酸钠-聚丙烯酰胺凝胶对其进行鉴定 还原条件下的电泳，然后进行荧光照相和 用显微密度计量法进行量化。四种新合成的主要蛋白质 相对分子质量分别为9kd、30kd、90kd和180kd 克拉拉细胞。9kd蛋白占释放蛋白的42%， 孵育4小时后，细胞内35S蛋白的含量为10%。9kd和 其他类型的细胞均不合成180kd蛋白。在……里面 此外，针对Clara细胞抗原制备的抗血清用于 确定洗涤液中存在9kd蛋白 兔子的肺。这些数据表明，克拉拉细胞制造和分泌 蛋白质不同于其他几种主要的蛋白质 肺细胞，其中一些蛋白质存在于 肺细胞外衬里。

The functions of the bronchiolar Clara cell are not known although numerous morphological investigations in many species have led to the hypothesis that the cell is secretory. The objectives of this research are to elucidate the secretory nature of the Clara cell, identify and characterize those secretions and determine their extracellular functions. We have developed a model system for the study of Clara cell functions and metabolism using cells isolated from the lungs of rabbits. Clara cells are dispersed from the lungs with pancreatic proteases and purified to over 90% by using, sequentially, a variety of techniques involving centrifugal elutriation, density gradient centrifugation, differential adherence and in vitro cultivation. Incubation of the isolated Clara cells with 35S-methionine for 4 hrs results in the radiolabeling of many intracellular proteins some of which were released into the incubation medium. Biosynthesis and secretion of proteins by Clara cell have been compared with those synthesized and secreted by other isolated and purified pulmonary cells including alveolar macrophages, Type II cells, and basal cells. The labeled cellular proteins and proteins released from the cells were identified by using sodium dodecylsulfate-polyacrylamide gel electrophoresis under reducing conditions followed by fluorography and quantified by microdensitometry. Four major newly synthesized proteins with molecular weights of 9 kd, 30 kd, 90 kd and 180 kd were released from the Clara cells. The 9 kd protein accounted for 42% of the released and 10% of the cellular 35S-protein after 4 hrs of incubation. The 9 kd and 180 kd proteins were not synthesized by any of the other cell types. In addition, antisera prepared against Clara cell antigens were used to identify the presence of the 9 kd protein in lavage effluents from the lungs of rabbits. These data demonstrate that Clara cells make and secrete proteins different from those made and secreted by several other major pulmonary cells and that some of those proteins are present in the pulmonary extracellular lining.