The in vivo effect of isocyanate-induced asthma on basophil histamine release

In vitro studies have suggested that basophils are involved in the asthmatic response to isocyanate. Classified by the type of airway response, three groups of patients exposed to isocyanate were studied: 1) nonreactive (n=3), 2) immediate responders (n=4), and 3) late responders (n=4). Basophil histamine release to concanavalin A (conA), FMLP, and anti-IgE was evaluated before and during the airway response. Histamine release significantly (P=0.009 for conA and 0.03 for anti-IgE) increased after exposure to isocyanate only in the group which had late bronchial response. Additionally, good correlation was found between baseline FEV₁/FVC% and degree of histamine release of basophils stimulated with conA. These findings support a role for basophils in the late asthmatic response to isocyanate.