INDUCIBLE NITRIC-OXIDE SYNTHASE DEMONSTRATED IN ALLERGIC AND IRRITANTCONTACT-DERMATITIS

Eight allergic patch test reactions, eight irritant skin reactions ind uced by 3% sodium lauryl sulphate and six normal controls were biopsie d. Biopsies were immunohistochemically stained with a mouse monoclonal antibody to inducible nitric oxide synthase (MOS), and staining was q uantified by computerised image analysis. Human chondrocytes induced t o express iNOS were used as a positive control. A significant increase in iNOS was found in both irritant and allergic contact dermatitis. T here were no differences in the distribution of expression of iNOS. Th e antibody used was confirmed by Western blotting not to crossreact wi th the endothelial isoform of nitric oxide synthase (NOS) but did cros s-react,vith a 150kDa protein, which may be neuronal NOS or an isoform of neuronal NOS.