Phosphorylation of a mast cell protein in response to treatment with anti-allergic compounds. Implications for the mode of action of sodium cromoglycate.

Challenge of rat peritoneal mast cells with anti-rat IgE induces a similar pattern of protein phosphorylation to that already reported for compound 48/80. Rapid phosphorylation of a mast cell protein, mol. wt 78,000, is induced by sodium cromoglycate and several chemically related anti-allergic agents in the absence of any challenge. Phosphorylation of this protein reflects their potency in inhibiting anti-IgE-induced histamine release. Compounds which inhibit histamine release by elevating intracellular cAMP levels do not induce phosphorylation. However, dibutyryl-cGMP induces phosphorylation of the 78,000 mol. wt protein in the absence of any challenge, at concns which inhibit IgE-dependent histamine release. Sodium cromoglycate appears to activate an endogenous control mechanism for switching off mediator release using a mechanism mediated by cGMP.