Phase-contrast microscopic studies using cinematographic techniques and scanning electron microscopy on IgE-mediated degranulation of cultured human mast cells.

Background: 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 investigate whether IgE-mediated activation of these cells is mediated by exocytosis.

Objective: To verify IgE-mediated activation of these cultured human mast cells morphologically.

Methods: The mast cells were raised from human umbilical cord blood cells in the presence of stem cell factor and interleukin-6. IgE-sensitized cultured human mast cells were activated by anti-IgE, and morphological changes of the cells were examined under phase-contrast microscopy using cinematographic techniques and scanning electron microscopy. Histamine release from the cells was measured with high-performance liquid chromatography.

Results: Under the condition in which a significant histamine release was observed from the mast cells, phase-contrast microscopy showed that the cultured human mast cells became swollen and extruded granules. Scanning electron microscopy disclosed the extrusion of smooth and round bodies from pores formed on the activated mast cell surface.

Conclusion: IgE-mediated histamine release from cultured human mast cells is accompanied by exocytosis morphologically, indicating that cultured human mast cells will help in studying the functional properties of human mast cells.