Effects of polyunsaturated fatty acids on calcium response and degranulation from RBL-2H3 cells

To investigate the biological activity of various polyunsaturated fatty acids (PUFAs) on the allergic reaction, we examined the effects of six PUFAs and two saturated fatty acids on calcium response and degranulation from rat basophilic leukemia (RBL-2H3) cells. Between 20 and 40 μM of six PUFAs (ω-6 series: arachidonic acid [AA, C20:4], γ-linolenic acid [γ-LN, C18:3] and linoleic acid [LA, C18:2]; ω-3 series: α-linolenic acids [α-LN, C18:3] and eicosapentaenoic acid [EPA, C20:5]; and ω-9 series: oleic acid [OLE, C18:1]), or two saturated fatty acids (stearic acid [STA, C18:0] and arachidic acid [AD, C20:0]) were used to examine the effects on calcium response and degranulation from RBL-2H3 cells. Calcium response was monitored using the fluorescent calcium indicator fura-2, while degranulation was monitored by measuring histamine release from the cells. Three ω-6 PUFAs (AA, α-LN and LA) dose-dependently increased the cytosolic free-calcium concentration and histamine release from RBL-2H3 cells. This phenomenon was specific to the ω-6 PUFAs, the ω-3 PUFAs (α-LA and EPA), ω-9 PUFA (OLE) and the saturated fatty acids (STA and AD) had no effect. The increase in the cytosolic free-calcium concentration caused by the ω-6 PUFAs depended on the existence of external calcium, cell viability and the cellular IP3 levels remained unchanged throughout the experiment. These results suggest that ω-6 PUFAs work as direct mediators of calcium signaling pathways in RBL-2H3 cells.