Neutrophil activation following TDI bronchial challenges to the airway secretion from subjects with TDI‐induced asthma

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Abstract
The immunopathological mechanism for occupational asthma induced by toluene diisocyanate (TDI) remains to be further clarified. There have been few reports suggesting involvement of neutrophils in inducing bronchoconstriction after TDI inhalation. To further understand the role of neutrophils in the pathogenesis of TDI-induced asthma. Eight TDI-induced asthmatic subjects were classified as group I, and five exposed workers who had complained of work-related symptoms and worked in the same workplace, but showed negative bronchial challenges were enrolled as controls (group II). Serum neutrophil chemotactic activity during TDI bronchial challenge test was measured by the Boyden chamber method. Induced sputum was collected before and after the TDI bronchial challenge test. The myeloperoxidase (MPO) and interleukin (IL) -8 levels in the sputum were measured using RIA and ELISA. Serum neutrophil chemotactic activity significantly increased at 10 min (P = 0.01), then decreased at 60 min (P = 0.02) and remained unchanged for up to 420 min (P = 0.07) in group I subjects, while no significant changes were found in group II subjects (P > 0.05). MPO and IL-8 were abundantly present in the sputum of all the TDI-induced asthmatic subjects and they increased significantly at 420 min after the bronchial challenges (P = 0.02, P = 0.03, respectively), while no significant changes were noted in group II subjects (P > 0.05). These findings support the view that activated neutrophils may contribute to bronchoconstriction induced by TDI which may be associated with IL-8 release.