The aniline blue fluorescence staining of eosinophilic granulocytes.

An aniline blue fluorescence staining technique specific for eosinophils was compared to haematoxylin and eosin to determine the percentages of eosinophils in the peripheral blood of patients with atopic or with allergic contact dermatitis. The aniline blue technique proved to be excellent for demonstrating eosinophilic granulocytes. Although the eosinophilic granulocytes were reasonably demonstrable in thin layers stained with haematoxylin and eosin, the aniline blue staining seems to be better in cases of doubt. Using the same techniques the presence of eosinophil granulocytes was studied in 5 punch biopsies taken from positive patch tests (after 48 h) and 5 biopsies from positive skin reactions after and intradermal injection with an atopic allergen (after 20--30 min). In all punch biopsies taken after an intradermal injection with an atopic allergen, eosinophilic granulocytes, often numerous, were seen in the vessels of the dermis. In punch biopsies taken from positive patch tests the eosinophilic granulocytes were seen scattered through the dermis in variable numbers.