CHARACTERISTICS OF HISTAMINE-RELEASE FROM CULTURED HUMAN MAST-CELLS

Background The mast cell is one of the important cells in the pathogen esis of allergic disorders. However, isolating human mast cells is a l aborious procedure. Recently, cultured human mast cells raised from um bilical cord blood cells have become available. It is necessary to exa mine whether these cells are useful in investigating the role of mast cells in human diseases. Objective The phenotype of mast cells depends on their anatomical sites. To examine which phenotype of mast cells t hese cultured mast cells most closely resemble, their ability to relea se was investigated. Methods The mast cells were raised from human umb ilical cord blood cells in the presence of stem cell factor and interl eukin-6. To determine the mast cell subtypes, the mast cells were immu nocytochemically stained for tryptase and chymase. The cultured mast c ells were then stimulated with various secretagogues, and histamine re lease was measured by a fluorometric technique using high-performance liquid chromatography. Results The immunocytochemical staining for mas t cell proteases revealed that virtually all cells contained tryptase, the definitive marker of mast cells, and that about a quarter of the cells contained chymase. Anti-IgE effectively stimulated these mast ce lls to release histamine in a dose-dependent, time-dependent manner. T he release was completed in about 30 min. One of the non-specific stim uli, calcium ionophore A23187, also induced histamine release in a dos e-dependent, time-dependent manner. In contrast, compound 48/80 and su bstance P failed to induce histamine release from these cells. Conclus ion Cultured human mast cells resemble lung mast cells in their abilit y to release histamine. They will help in studying the functional prop erties of human mast cells and may contribute to clarifying the pathop hysiology of human allergic diseases.