Inhibitory effects of natural flavonoids on secretion from mast cells and neutrophils

30 natural flavonoids were tested for their inhibitory action on stimulated secretion from rat mast cells and rabbit neutrophils in vitro. There was no correlation between the degrees of inhibitory activity of the flavonoids on the two cell types, or upon the inhibition of the Ca2+ transporting ATPase from sarcoplasmic reticulum. The inhibitory action of flavonoids on mast cells is believed to be at the level of the receptor directed Ca2+ channels in the plasma membrane. For neutrophils it is demonstrated that inhibitory flavonoids do not significantly alter Ca2+ movements across the plasma membrane; nor do they reduce the extent of ligand binding to its receptor. This evidence suggests that flavonoids do not have a common mode of inhibition on these cell types. Rather, the flavonoids must have more specific effects on the different systems examined.