Histamine Release and Inflammatory Cell Infiltration in Airway Mucosa in Methylene Diphenyl Diisocyanate (MDI)-Induced Occupational Asthma
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Although methylene diphenyl diisocyanate (MDI) is widely used in industries, there have been few studies of the pathogenic mechanisms of MDI-induced occupational asthma (MDI-OA).
We performed immunohistochemical analyses, measured inflammatory mediators and cytokines, and quantified histamine release (HR) from peripheral basophils in MDI-OA patients. Thirteen MDI-exposed workers (five MDI-OA, two MDI-induced esoinophilic bronchitis, and six asymptomatic exposed controls, AEC) were enrolled.
Results and Discussion
Immunochemical analyses indicated significantly increased anti-eosinophilic cationic protein-stained cells in MDI-OA patients as compared with controls (P < 0.05). Sputum eosinophil cationic protein levels were increased after MDI-specific inhalation challenge test in MDI-OA/EB patients (P < 0.02). Sputum eosinophil counts were highly correlated with IL-8 and MMP-9 levels (P < 0.05 and P < 0.01, respectively). Basophil HR was significantly increased in MDI-OA patients after stimulations with anti-IgG4 and MDI–human serum albumin conjugates (both P < 0.05). Eosinophil activation is a major feature of airway inflammation in MDI-OA patients. Increased HR by MDI may contribute to the pathogenic mechanisms of MDI-OA.
KeywordsEosinophil mast cell MDI occupational asthma
asymptomatic exposed controls
eosinophil cationic protein
human serum albumin
methylene diphenyl diisocyanate
methylene diphenyl diisocyanate-induced occupational eosinophilic bronchitis
methylene diphenyl diisocyanate-induced occupational asthma
methylene diphenyl diisocyanate-induced occupational asthma or eosinophilic bronchitis
toluene diisocyanate-induced occupational asthma
tissue inhibitor of metalloproteinase-1
vascular endothelial growth factor
work-related respiratory symptoms
We would like to thank Dr. Adam Wisnewski of Yale University for providing the MDI–HSA conjugates used in this study. This study was supported by a grant from the Korean Health 21 R&D Project of the Ministry of Health and Welfare, Republic of Korea (A050571).
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