β‐ADRENOCEPTOR‐MEDIATED INHIBITION OF MEDIATOR RELEASE FROM HUMAN PERIPHERAL BLOOD‐DERIVED MAST CELLS

Abstract

1. Mast cells cultured from human peripheral blood have been used as a cell model for functional studies of human mast cells, particularly human lung mast cells. However, the beta-adrenoceptor subtype expressed by these cultured cells has not been identified. The aim of the present study was to characterize pharmacologically the beta-adrenoceptors involved in the suppression of IgE-mediated release of mediators, including histamine, prostaglandin (PG) D2 and leukotriene (LT) C4 from cultured mast cells. 2. Mast cells were cultured from mast cell progenitors isolated from peripheral blood in the presence of 200 ng/mL stem cell factor and 50 ng/mL interleukin-6. Mast cells were sensitized with human myeloma IgE, treated with beta-adrenoceptor agonists or antagonist and then challenged with anti-human IgE. The release of histamine, PGD2 and LTC4 from mast cells was determined. 3. Both isoprenaline and salbutamol inhibited anti-IgE-induced release of histamine, PGD2 and LTC4 from cultured mast cells in a dose-dependent manner. Isoprenaline was a more potent inhibitor than salbutamol. The pD2 values for the inhibition of the release of histamine, PGD2 and LTC4 were 7.37 +/- 0.12, 8.38 +/- 0.23, 8.85 +/- 0.23, respectively, for isoprenaline and 6.96 +/- 0.12, 7.65 +/- 0.36, 7.91 +/- 0.64, respectively, for salbutamol. The selective beta3-adrenoceptor agonist BRL-37344 failed to affect anti-IgE-induced histamine release from cultured mast cells. 4. The selective beta2-adrenoceptor antagonist ICI 118 551 (108 mol/L) strongly reversed the concentration-dependent suppression of histamine release by isoprenaline and salbutamol; however, the selective beta1-adrenoceptor antagonist atenolol (106 mol/L) did not have any effect. 5. These results indicate that both isoprenaline and salbutamol act at beta2-adrenoceptors to suppress IgE-mediated mediator release from cultured human mast cells.