Mast cells, basophils, and eosinophils: distinct but overlapping pathways for recruitment

Mast cells, basophils and eosinophils are bone marrow-derived cells that co ntribute to a variety of allergic and other immune responses. For example, they are relatively abundant at mucosal sires where allergic inflammation i s occurring, and their activation and release of preformed and newly-genera ted mediators at these sires is considered central to the pathophysiology o f allergic diseases. Given their involvement in allergic and other diseases , it is important to understand how these cells are selectively recruited i nto tissues. These cells share many phenotypic features, including those in volved in adhesion and migration, yet their localization within a given tis sue can be quite distinct. In addition, there are examples of selective rec ruitment of one cell type without the others. From studies with human cells , it is now clear that mast cells, basophils and eosinophils share a number of recruitment pathways with one another and with other cells, bur that ea ch possesses unique adhesion and migration responses that can contribute to their preferential accumulation. This review will focus on cell surface st ructures implicated in adhesion and migration responses of human mast cells , basophils and eosinophils. Both shared and selective expression of these molecules will be highlighted, as well as differences in their relative lev els of expression. Cell type-specific stimuli that alter adhesion and migra tion responses will also be considered.