Surfactant protein C is expressed in alveolar type II cells but not in Clara cells of rat lung.
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.
Kalina
M
M
Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.
Mason
R J
RJ
Shannon
J M
JM
D000818:Animals; D001980:Bronchi / Q000737:chemistry / Q000166:cytology; D004848:Epithelium / Q000737:chemistry; D008168:Lung / Q000737:chemistry* / Q000166:cytology; D016676:Macrophages, Alveolar / Q000737:chemistry; D011510:Proteolipids / Q000032:analysis*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats
D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger