Inhibition of eosinophils degranulation by Ketotifen in a patient with milk allergy, manifested as bronchial asthma--an electron microscopic study.

Electron microscopic studies provided evidence that a patient with cow's milk allergy, manifested as bronchial asthma, has prominent eosinophil granule discharge, attributable to the release of cytotoxic major basic protein (MBP). This finding illustrates a critical role of eosinophil MBP in anaphylactic injury induced by food allergen. Patient white blood cells pretreated with Ketotifen revealed intact ultrastructure of eosinophils granules and cytoplasm. Inhibition of eosinophils degranulation by Ketotifen demonstrates a new pharmacologic mode of action of this anti-allergic, anti-anaphylactic agent.