Influenza A virus enhances basophil histamine release and the enhancement is abolished by carbohydrates

Basophil histamine release was studied in leukocyte suspensions from normal individuals and from patients allergic to house dust mite or birch pollen. Mediator release caused by IgE‐mediated reactions was examined by stimulating the cells with anti‐IgE or specific antigens, and the calcium ionophore A23187 was used for a non‐immunological histamine release. In all experiments influenza A virus caused a synergistic enhancement of the mediator release and the potentiation was abolished by galactose (10 ⁻² to 10⁻⁶ M) and by 10⁻⁶ to 10⁻³ M of N‐acetylglucosamine, alpha‐methyl‐D‐glucoside, alpha‐methyl‐D‐mannoside, N‐acetylneuraminic acid and lactose, but not by glucose. Wash‐out experiments show that the sugars prevent the aggravation of mediator release by a binding of sugar to the basophil cell membrane, thereby causing a blockade of binding sites responsible for the potentiating effect of virus.