['[oli', 'iain', 'dememenanealionmeanensemnantiichiiamememmmienaend', 'smbhtnmnsienne', 'ommstnenedtt', 'Mamiameniamea’', 'yah’', 'a', '—areneeranere', 'nvm', 'remmamnereraa', 'hy', 'emit', 'ttt', 'i', 'a', '4', 'a', 'am', 'fh', 'ae', 'Mw', ' ', 'ULTRASTRUCTURAL', 'DEMONSTRATION', 'OF', 'CATALASE', 'AND', 'PEROXIDASE', 'ACTIVITY', 'IN', 'PULMONARY', 'ALVEOLAR', 'MACROPHAGES', 'The', 'release', 'of', 'intracellular', 'enzymes', 'by', 'the', 'host', 'defense', 'cells', 'of', 'the', 'lung', 'may', 'be', 'the', 'crucial', 'key', 'to', 'understanding', 'the', 'initiating', 'pathophysiologic', 'mechanisms', 'by', 'which', 'lung', 'injury', 'occurs.', 'The', 'pulmonary', 'alveolar', 'macrophage', '(AM)', 'is', 'the', 'key', 'phagocytic', 'cell', 'of', 'the', 'host', 'defense', 'system,', 'responsible', 'for', 'physically', 'ingesting', 'and', 'renoving', 'both', 'organic', 'and', 'inorganic', 'potential', 'toxins', 'that', 'deposit', 'on', 'alveolar', 'surfaces.', 'AM', 'are', 'frequently', 'increased', 'in', 'mmber', 'in', 'the', 'early', 'phases', 'of', 'many', 'lung', 'diseases,', 'and', 'by', 'this', 'increase', 'in', 'cell', 'number', 'potentially', 'enhance', 'the', 'amount', 'of', 'enzymatic', 'activity', 'available', 'to', 'further', '-', 'cause', 'lung', 'injury.', 'Although', 'catalase', 'activity', 'and', 'a', 'catalase-dependent', 'peroxidase', 'activity', 'have', 'been', 'demonstrated', 'biochemically', 'in', 'the', 'AM,', 'the', 'role', 'of', 'these', 'enzymes', 'in', 'interstitial', 'lung', 'disease', 'and', 'their', 'site', 'of', 'localization', 'remain', 'controversial.', 'The', 'purpose', 'of', 'our', 'experiments', 'was', 'to', 'localize', 'the', 'enzyme', 'activity', 'of', 'catalase', 'and', 'peroxidase', 'by', 'ultrastructural', 'histochemistry', 'in', 'the', 'AM.', 'AM', 'harvested', 'from', 'guinea', 'pigs', 'by', 'saline', 'lavage', 'were', 'fixed', 'for', 'two', 'hours', 'in', '2.0%', 'glutaraldehyde', 'in', '0.1', 'M', 'cacodylate', 'buffer', '(pH', '7.4)', 'and', '2.0%', 'calcium', 'chloride,', 'then', 'incubated', 'in', 'the', 'dark', 'for', 'sixty', 'minutes', 'in', 'dianino-', 'benzidine', '(DAB)', 'st', 'pH', '10.5', 'or', 'pH', '7.6', 'and', '0.06%', 'H202', 'and', 'post-fixed', 'in', '2.0%', 'osmiun', 'tetroxide.', 'Catalase', 'activity', 'was', 'localized', 'primarily', 'to', 'homogenous', 'granules,', 'oval-to-round', 'in', 'shape', 'and', '0.1', 'to', '0.3', 'microns', 'in', 'size.', 'This', 'reaction', 'product', 'deposited', 'uniformly', 'over', 'the', 'granular', 'matrix,', 'often', 'obscuring', 'a', 'single', 'limiting', 'membrane', 'of', 'the', 'granules.']