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Increased expression of human leukocyte antigen-DR on pulmonary macrophages in bronchopulmonary dysplasia
J D Jacobson1, W E Truog, D R Benjamin
1Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
Abstract:
We used an immunoperoxidase method to examine the expression of the immune activation marker HLA-DR on pulmonary tissue obtained at autopsy from 14 patients dying of bronchopulmonary dysplasia. Controls consisted of 16 age-matched, sex-matched children dying of noncardiac, nonrespiratory, noninfectious illnesses or as a result of motor vehicle accidents. We did not observe aberrant expression of HLA-DR on pulmonary endothelial cells. Positive staining appeared exclusively on macrophages. We quantitated the expression of antigen by counting the number of positive macrophages and total macrophages/monocytes per high power field. Bronchopulmonary dysplasia patients displayed significantly greater numbers of both positive and total macrophages compared with the control group (p < 0.05). The percent positive macrophages also was significantly higher in the bronchopulmonary dysplasia patients (p < 0.005). We also examined a group of patients dying with infant respiratory distress syndrome. There was no significant difference in number of total macrophages in this group compared with age-matched controls.
Insights
Macrophages expressing HLA-DR are elevated in infants with bronchopulmonary dysplasia. This immune marker suggests increased pulmonary inflammation in this condition, unlike infant respiratory distress syndrome.
Area of Science:
- Immunology
- Pulmonary Medicine
- Pathology
Background:
- Bronchopulmonary dysplasia (BPD) is a chronic lung disease in infants.
- Pulmonary inflammation plays a role in BPD pathogenesis.
- Human Leukocyte Antigen - antigen D Related (HLA-DR) is an immune activation marker.
Purpose of the Study:
- To investigate the expression of HLA-DR on pulmonary tissue in patients with BPD.
- To compare HLA-DR expression in BPD patients with control groups.
Main Methods:
- Autopsy pulmonary tissue samples were analyzed using the immunoperoxidase method.
- HLA-DR expression was assessed on macrophages and endothelial cells.
- Quantification involved counting positive and total macrophages/monocytes per high power field.
Main Results:
- HLA-DR expression was exclusively observed on macrophages, not pulmonary endothelial cells.
- Patients with BPD showed significantly higher numbers of total and HLA-DR-positive macrophages (p < 0.05).
- The percentage of HLA-DR-positive macrophages was also significantly higher in BPD patients (p < 0.005).
- No significant difference in total macrophages was found in infant respiratory distress syndrome patients compared to controls.
Conclusions:
- Increased pulmonary macrophages expressing HLA-DR indicate heightened immune activation in bronchopulmonary dysplasia.
- This finding suggests a role for macrophage-mediated inflammation in BPD.
- Infant respiratory distress syndrome did not show similar alterations in macrophage counts.
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