Expression of dipeptidyl aminopeptidase IV activity in human lung carcinoma

Dipeptidyl aminopeptidase IV (DAP IV) staining was examined in various histological types of lung carcinomas to evaluate this enzyme activity. A total of 45 lung carcinomas were examined for their enzyme activity. Almost all (93.1%) cases of adenocarcinoma were positive for DAP IV activity, whereas all cases of squamous cell carcinoma, small cell carcinoma, large cell carcinoma and carcinoid were negative. DAP IV activity of microsomes in lung carcinomas was significantly higher in papillary adenocarcinomas than in squamous cell carcinomas. These data suggest that DAP IV may be a good marker to distinguish adenocarcinoma from other histological types of lung carcinoma.