Kalina M, Mason R J, Shannon J M
Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.
Am J Respir Cell Mol Biol. 1992 Jun;6(6):594-600. doi: 10.1165/ajrcmb/6.6.594.
The expression of the surfactant-associated proteins in bronchiolar cells remains to be defined. We used in situ hybridization to identify sites of message expression of the surfactant-associated proteins A, B, and C (SP-A, SP-B, and SP-C) in adult and fetal rat lung. The expression of these messages by in situ hybridization was also compared with the localization of SP-A by immunocytochemistry. The localization of SP-A was used to identify type II cells and nonciliated bronchiolar epithelial (Clara) cells in these sections. The cRNA antisense probes for SP-A, SP-B, and SP-C appeared to hybridize over type II cells. Sense probes showed no localization or apparent specific hybridization. Messages for both SP-A and SP-B were also found in nonciliated bronchiolar epithelial (Clara) cells. However, no message for SP-C was observed in these cells. Clara cells from terminal to large bronchioles lacked detectable mRNA for SP-C. Expression of surfactant protein mRNAs was not detectable in type I cells, alveolar macrophages, interstitial cells, or vascular cells. Similarly, in fetal rat lung the messages for SP-A and SP-B but not SP-C were detected in bronchiolar cells. We conclude that rat Clara cells do not express SP-C mRNA, and thus SP-C can be regarded as a specific marker for rat type II cells.
支气管细胞中表面活性物质相关蛋白的表达情况仍有待明确。我们采用原位杂交技术来确定成年和胎鼠肺中表面活性物质相关蛋白A、B和C（SP-A、SP-B和SP-C）的信使表达位点。通过原位杂交对这些信使的表达情况与免疫细胞化学法检测的SP-A定位情况进行了比较。利用SP-A的定位来识别这些切片中的Ⅱ型细胞和无纤毛支气管上皮（克拉拉）细胞。用于SP-A、SP-B和SP-C的cRNA反义探针似乎在Ⅱ型细胞上发生杂交。正义探针未显示出定位或明显的特异性杂交信号。在无纤毛支气管上皮（克拉拉）细胞中也发现了SP-A和SP-B的信使。然而，在这些细胞中未观察到SP-C的信使。从终末细支气管到大气道的克拉拉细胞均缺乏可检测到的SP-C mRNA。在Ⅰ型细胞、肺泡巨噬细胞、间质细胞或血管细胞中未检测到表面活性物质蛋白mRNA的表达。同样，在胎鼠肺中，在支气管细胞中检测到了SP-A和SP-B的信使，但未检测到SP-C的信使。我们得出结论，大鼠克拉拉细胞不表达SP-C mRNA，因此SP-C可被视为大鼠Ⅱ型细胞的特异性标志物。
