Ultrastructure of basophilic leukocytes and mast cells in normal and cutaneous basophil hypersensitivity-reacted guinea pig dermis.

Basophilic leukocytes and mast cells in guinea pig dermis in normal and cutaneous basophil hypersensitivity (CBH) reaction were examined by light and electron microscopy. Basophils were rare in the normal dermis and predominantly revealed in the CBH-reacted skin. Some infiltrating basophils of the reacted displayed an immediate attachment to mast cells. Cytoplasmic continuities were partially seen between them. They were most plentiful at 48 h after phytohemagglutinin injection and decreased in number thereafter. The basophils contained three types of granule. The vast majority of granules were Type I granules, basophil-specific granules. Type II granules were less frequently encountered and resembled a mast cell granule in the fine structure. Type III granules were scant and small-cored vesicles.