SummaryBackgroundThe mtist cell is one of the important cells In the pathogenesis of allergic disorders. However, isolating human mast cells is a laborious procedure. Recently, cultured human mast cells raised from umbilical cord blood cells have become available. It is necessary to examine whether these cells are useful in investigating the role of mast cells in human diseases.ObjectiveThe phenotype of mast cells depends on their anatomical sites. To examine which phetiotype of mast cells these cultured mast cells most closely resemble, their ability to release was investigated.MethodsThe mast cells were raised from human umbilical cord blood cells in the presence of stem cell factor and interIeukin‐6. To determine the mast cell subtypes, the mast cells were immunocytochemically stained for tryptase and chymase. The cultured mast cells were then stimulated with various secretagogues, and histamine release was measured by a fluorometric technique using high‐performance liquid chromatography.ResultsThe immunocytochemical staining for mast 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‐TgE effectively stimulated these mast cells to release histamine in a dose‐dependent, lime‐dependent manner. The release was completed in about 30 min. One of the non‐specific stimuli, calcium ionophore A23I87. also induced histamine release in a dose‐dependent, time‐dependent manner. In contrast, compound 48/80 and substance P failed to induce histamine release from these cells.ConclusionCultured human mast cells resemble lung mast cells in their ability to release histamine. They will help in studying the functional properties of human mast cells and may contribute to clarifying the pathophysiology of human al
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