Degranulation of basophilic leukocytes in allergic contact dermatitis reactions in man.

Basophilic leukocytes participating in allergic contact dermatitis in man underwent progressive degranulation over the course of several days after skin test. Less than 10% of basophils were degranulated in 24-hr reactions, but more than 60% were degranulated by 72hr. In electron microscopic individual basophil granules developed looser packing of particles by finely granular material, and eventual loss of all visible granule contents, changes that were progressive between 2- and 3-day reactions.