Interleukin-18 primes human basophilic KU812 cells for higher leukotriene synthesis

The human basophilic cell line KU812 that is an established tool for studying the function of human basophils, is differentiated into mature basophils by interleukin (IL-3) or other agents. However, whether leukotrienes (LTs)-synthesis is affected by cytokines in KU812 cells remains unknown. KU812 cells were incubated with IL-3, IL-4, IL-6, IL-13 or IL-18 for up to 14 days. The A23187 stimulated- and IgE cross-linked-synthesis of LTC ₄ and LTB ₄ were measured using an enzyme immunoassay (EIA). The expression of messenger RNA (mRNA) for LT-synthesizing enzymes was examined by reverse transcriptase polymerase chain reaction (RT-PCR), and the expression of 5-lipoxygenase (5-LO) was examined by immunostaining. Incubation with IL-3 (10 ng/ml) and IL-18 (10 ng/ml) induced the expression of 5-LO. A23187stimulated LT-synthesis and IgE cross-linked LT-synthesis were enhanced after incubation with IL-3 or IL-18. These results indicated that IL-3 and IL-18 primed human basophils for higher LT-synthesis. Thus, both IL-3 and IL-18 might be important factors for regulating LT-synthesis during the differentiation of human basophils.