Intrinsic asthma and bacterial histamine release via lectin effect.

Bacteria-induced histamine release from basophil leukocytes was observed in vitro in both children with intrinsic asthma (IA) as well as in normal individuals. In vivo the release is suggested to take place only in the lung of IA patients, where a defective pulmonary barrier would permit the bacteria to enter, but not in healthy individuals. The study indicates that two different mechanisms of bacterial histamine release might exist, an IgE-mediated reaction and a non-immunological mechanism consisting of a direct interaction with the basophil cell surface. The non-allergic mechanism might depend on a lectin effect where bacterial surface lectins interact with the basophil cell surface leading to release of histamine. Inhibition studies with carbohydrates suggest a multi-lectin reaction in the bacterial histamine release involving several types of lectins on the bacterial membrane reacting with different carbohydrate moieties on the cell surface of basophil leukocytes.