Changes in filament actin accompanying IgE-dependent and -independent histamine release from IL-3-dependent cultured...

When cord blood mononuclear cells were cultured in the presence of rhIL-3 for 5 weeks or more, 40-90% of cultured cells became morphologically mature basophils. We analyzed the kinetics of histamine release, changes in filament actin (F-actin), and movement of intracellular Ca2+ ([Ca2+]i) induced by IgE-dependent (anti-IgE) and -independent (fMLP) stimuli in these cultured basophils. Anti-IgE and fMLP released 24.5 +/- 5.4% and 14.5 +/- 4.5% histamine from the cells, respectively. Anti-IgE caused actin polymerization with a peak response at 15 min, which began much later than the elevation of [Ca2+]i. In contrast to anti-IgE stimulation, fMLP induced rapid actin polymerization with a peak response at 30 s in correlation with kinetics of histamine release. Our results indicate that cord blood-derived cultured basophils show similar cell functions to mature basophils, and are useful models with which to investigate the mechanisms of degranulation, specifically when a large amount of highly purified cells are required.