KU812 cells are well-established tool for studying the mediators in human basophils. However, it not known whether the production of leukotrienes (LTs), important mediators of the allergic responses, are induced by biological stimuli, such as cytokines.

KU812 cells were incubated with various concentrations of IL-3, IL-4, or IL-18 (0-100ng.ml) for several times (0-14 days). We then examined the expression of messenger RNA (mRNA) for cytosolic phospholipase A (cPLA2), 5-lipoxygenase (5-LO) and LTC4 synthase by reverse transcriptase polymerase chain reaction (RT-PCR), and the expression of 5-LO was examined by immunostaining in the cells. We also examined the A23187-stimulated release of LTC4 by enzyme immunoassay (EIA).

After 14 days-incubation with L-3 (10ng/ml) and IL-18 (10ng/ml) increased mRNA and protein expression for 5-LO. A23187-stimulated release of LTC4 was significantly increased from 4.3 ± 0.3 pg/10⁶ cells to 32.5 ± 5.2 pg/10⁶ cells by IL-3 and to 11.3 ± 1.6 pg/10⁶ cells by IL-18.

These results indicate that IL-3 and IL-18 induce 5-LO and LT-synthesis. IL-3- and/or IL-18-treated KU812 cells are useful models for investigation for LT synthesis in human basophils.