Immunohistochemical detection of GM‐CSF, IL‐4 and IL‐5 in a murine model of allergic bronchopulmonary aspergillosis

BACKGROUND: Granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin-4 (IL-4) and IL-5 are important in tissue eosinophil accumulation and high IgE production in allergic inflammatory reaction. OBJECTIVE: We examine lung GM-CSF, IL-4 and IL-5 expression in a murine model of allergic bronchopulmonary aspergillosis (ABPA) characterized by eosinophil and lymphocyte lung infiltration and elevated serum IgE level. METHODS: C57BL/6 mice were intranasally treated three times a week for 1, 2 or 3 week(s) with Aspergillus fumigatus (Af) antigen or saline and were sacrificed on days 7, 14 and 21. Immunohistochemical analyses for GM-CSF, IL-4 and IL-5 were performed on lung sections. RESULTS: Af treatment induced a remarkable pulmonary eosinophil influx. Increased numbers of lung T lymphocytes and GM-CSF positive cells were observed on days 14 and 21. IL-4 and IL-5 positive cells were increased significantly only on day 14. Immunostained serial sections showed that most (> or = 98%) cytokine positive cells were CD3 positive. Few eosinophils (< 2% of cytokine positive cells) were immunoreactive for GM-CSF and IL-5. Significant correlations were found between the number of GM-CSF and IL-5 positive cells, and the number of eosinophils in Af-treated lung (r = 0.62, P < 0.05 and r = 0.52, P < 0.05 respectively), and between the number of IL-4 positive cells and the serum total IgE level (r = 0.64, P < 0.01). CONCLUSIONS: Our data suggest a role for T lymphocyte GM-CSF, IL-4 and IL-5 in Af-induced mouse pulmonary eosinophilia and increased serum IgE production and further support the importance of T helper (TH2) cells in the pathogenesis of ABPA.