[Human basophilic granulocytes and mast cells: mediators between allergic inflammation and the specific immune system].

Basophils and mast cells represent important effector cells in allergic inflammation. Furthermore, these cell types are suggested to play a role in the pathogenesis of other forms of chronic inflammation and in the maintenance of tissue homeostasis. Recent studies provided new information on the morphology, development, distribution and effector function of the histamine-containing cells. Particularly the identification of new surface membrane molecules such as CD40 ligand on basophils or c-kit on mast cells, and of new triggering agents and modulators of mediator release such as IL-3, IL-5, GM-CSF and nerve growth factor (for basophils) or c-kit ligand (for mast cells) allows a better understanding of the regulation of these cell types. The regulating cytokines are produced by lymphocytes and tissue cells. On the same time, membrane proteins and soluble mediators of basophils and mast cells regulate tissue and immune functions. Thus, basophils and mast cells are not only effectors but also regulators of inflammation. It is, therefore, tempting to speculate that both cell types play an important role as mediator cells between the unspecific effector level and the specific antigen-recognizing cells of the host immune defense system. This review is mostly restricted to the human system.