IMMUNOHISTOCHEMICAL CHARACTERIZATION OF NITRIC-OXIDE SYNTHASE ACTIVITY IN SQUAMOUS-CELL CARCINOMA OF THE HEAD AND NECK

This study was designed to investigate the presence of nitric oxide in human squamous cell carcinoma of the head and neck. We localized the activity of nitric oxide synthase in these tumors through immunohistoc hemical analysis using antibodies to L-citrulline (a byproduct of nitr ic oxide synthase), to inducible nitric oxide synthase, and to constit utive nitric oxide synthase, We found presence of inducible enzyme in squamous cells throughout these tumors, with the highest intensity sta ining occurring directly around keratin pearls, Our findings suggest t hat inducible nitric oxide synthase activity is present in squamous ce ll carcinomas of the head and neck, leading us to conclude that induci ble nitric oxide synthase may play a significant role in tumor growth.