title: Cathepsin B-like cysteine proteinase activity in sputum and immunohistologic identification of cathepsin B in alveolar macrophages.
abstract: Cathepsin B-like cysteine proteinase activity was measured, using a fluorimetric assay, in sputum samples from 27 subjects with chronic obstructive airways disease. Thirteen of the subjects had a current acute respiratory infection. Enzyme activity was detected in 11 of the 13 infected and 12 of the 14 noninfected samples. The mean cathepsin B activity observed in the infected samples was significantly greater than that of the noninfected samples. Most of the cathepsin B-like activity in sputum represented enzyme in free solution but a small proportion appeared to be complexed with alpha 2-macroglobulin. Immunohistochemical localization of cathepsin B in human lung tissue sections detected the enzyme only within macrophages.
mesh_terms: D002401:Cathepsin B; D002403:Cathepsins / Q000032:analysis* / Q000378:metabolism; D003546:Cysteine Endopeptidases; D010450:Endopeptidases / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D008173:Lung Diseases, Obstructive / Q000201:enzymology*; D008264:Macrophages / Q000201:enzymology*; D011650:Pulmonary Alveoli / Q000201:enzymology*; D013183:Sputum / Q000201:enzymology
chemical_list: D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B