Assessment of chromium allergy: features of patch test reactions at electron microscopic resolution

The possible correlation of clinically recorded test reactions and morphological changes at electron microscopic resolution in human subjects allergic to chromate (CrVI) was investigated. The effect of simple occlusion and of vehicles, e.g. distilled water, an alkaline buffer, and petrolatum was also studied 72 hours after application. The results indicate that even simple occlusion causes reactive changes in living epidermal cells. These changes become conspicuous in occlusion with distilled water, more pronounced with petrolatum, and were destructive in the case of the alkaline buffer. Chromate solutions produced varying degress of morphological change but were less pronounced in a vehicle of distilled water, compared with the changes seen when the chromate was combined with the alkaline buffer. Destructive cellular changes were observed in the electron microscope even in sections from test ares where no macroscopical reactions were recorded. When the clinical evaluation of hypersensitivity was done 72 hours after the application of the patch test the morphological changes were too advanced to provide specific pathognomonic information.