Lysosomal and cytosolic sialidases in rabbit alveolar macrophages: demonstration of increased lysosomal activity after in vivo activation with bacillus Calmette-Guerin.
Sialidase activity was assayed in homogenized rabbit alveolar macrophages using a fluorogenic substrate: sodium 4-methylumbelliferyl-alpha-D-neuraminate. After differential centrifugation one acid-active enzyme (optimum pH 4.2) was detected in the 16,000 X g pellet that contained lysosomes, mitochondria and peroxisomes. A second activity, with an optimum pH of 5.4, was found in the cytosolic fraction. The acid-active sialidase accounted for more than 95% of the total sialidase activity in crude homogenate. When alveolar macrophages were collected from rabbits stimulated with bacillus Calmette-Guerin (BCG), the acid-active sialidase specific activity was increased 2.5-fold whereas other lysosomal enzymes such as N-acetylglucosaminidase and beta-galactosidase were stable. The cytosolic sialidase activity did not change.
D000818:Animals; D002448:Cell Adhesion; D002458:Cell Fractionation; D003600:Cytosol / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008247:Lysosomes / Q000201:enzymology*; D008262:Macrophage Activation; D008264:Macrophages / Q000201:enzymology* / Q000276:immunology; D008297:Male; D009163:Mycobacterium bovis / Q000276:immunology*; D009439:Neuraminidase / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000166:cytology*; D011817:Rabbits
D009439:Neuraminidase