Singh G, Katyal S L, Brown W E, Collins D L, Mason R J
Department of Pathology, University of Pittsburgh School of Medicine, PA.
Am Rev Respir Dis. 1988 Nov;138(5):1261-7. doi: 10.1164/ajrccm/138.5.1261.
A 14 kDa basic protein isolated from rat lung lavage was demonstrated to be lysozyme by its amino acid sequence analysis. An antiserum to rat lysozyme stained type II pneumocytes and alveolar macrophages. In rat lungs, no staining of the airway cells was noted. Lysozyme was detectable in type II pneumocytes by immunocytochemistry and by a quantitative immunoassay of lung homogenates of fetal lungs at Day 20 of gestation. An increase in the lysozyme content of the lung with increasing gestational and postnatal age of the rat was noted. In adult animals, lysozyme accounts for about 169.0 micrograms/g of wet lung weight and 0.3% of the soluble proteins in lung homogenate. Lysozyme constitutes about 6.6% of the total soluble proteins in rat lung lavage. Metabolic labeling and immunoprecipitation were used to demonstrate that rat type II pneumocytes synthesize and secrete lysozyme in vitro. However, in human lungs, lysozyme was identified in serous submucosal glands but not in alveolar type II pneumocytes. The results demonstrate differential distribution of a secretory protein in rodent and human lungs and indicate that in the rat lysozyme could be used as an immunohistologic marker for type II pneumocytes and as an indicator of secretory activity and maturation of type II pneumocytes.
通过氨基酸序列分析证实，从大鼠肺灌洗液中分离出的一种14 kDa碱性蛋白为溶菌酶。抗大鼠溶菌酶抗血清可对II型肺泡上皮细胞和肺泡巨噬细胞进行染色。在大鼠肺中，未观察到气道细胞有染色现象。通过免疫细胞化学和对妊娠第20天胎肺匀浆的定量免疫测定，可在II型肺泡上皮细胞中检测到溶菌酶。随着大鼠妊娠和出生后年龄的增加，肺中溶菌酶含量也随之增加。在成年动物中，溶菌酶约占湿肺重量的169.0微克/克，占肺匀浆中可溶性蛋白的0.3%。溶菌酶约占大鼠肺灌洗液中总可溶性蛋白的6.6%。采用代谢标记和免疫沉淀法证明，大鼠II型肺泡上皮细胞在体外合成并分泌溶菌酶。然而，在人肺中，溶菌酶存在于浆液性黏膜下腺中，而在II型肺泡上皮细胞中未发现。这些结果表明，一种分泌蛋白在啮齿动物和人肺中的分布存在差异，并表明在大鼠中，溶菌酶可作为II型肺泡上皮细胞的免疫组织学标记物，以及II型肺泡上皮细胞分泌活性和成熟度的指标。
