A pathologic study of allergic bronchopulmonary aspergillosis

Area of Science:

• Pulmonary Medicine
• Immunology
• Pathology

Background:

• Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus fumigatus.
• Cystic fibrosis (CF) patients are at increased risk for developing ABPA.
• Understanding ABPA pathogenesis is crucial for effective treatment strategies.

Observation:

• A lung biopsy from a 10-year-old boy with CF and ABPA showed bronchocentric inflammation with eosinophils, lymphocytes, plasma cells, and monocytes.
• Microscopy revealed intact elastin in blood vessels but disruption in bronchioles.
• Immunofluorescence detected eosinophil major basic protein deposited extracellularly and within macrophages, with some lymphocytes staining positive for IgE.

Findings:

• Immunoperoxidase staining confirmed septate hyphae of Aspergillus in the lung parenchyma.
• Increased interleukin-2 positive T cells were observed, with a helper to suppressor cell ratio of approximately 2:1.
• Extracellular deposition of eosinophil major basic protein suggests a role in tissue damage.

Implications:

• Advanced immunohistologic techniques provide deeper insights into ABPA pathogenesis.
• Findings highlight the complex interplay between fungal elements, eosinophils, and T cells in CF-related ABPA.
• Further research can explore targeted therapies based on these immunopathologic mechanisms.