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Published on: August 7, 2017
Pulmonary macrophage counts in deceased infants: baseline data for further study of infant mortality
K Delaney1, R Hanzlick, M Wolfe
1School of Public Health, University of Albany, State University of New York, USA.
Abstract:
Infant lung samples were obtained prospectively at autopsy by medical examiner pathologists in five areas of the United States and regardless of the cause of death. Four sections were examined for each case and were taken from the anterior and posterior aspects of the right and left upper lung lobes. Lung sections were stained with HAM-56 immunostain, which is specific for macrophages. Sixty-one cases were evaluated for the study. Three pathologists independently counted the number of macrophages per 40x field (10x ocular) in 10 contiguous fields near the center of each lung section examined. There was good agreement between pathologists on the average number of macrophages observed in each case. The mean macrophage count for all fields counted was 16.5 per 40x field (range 0-136), and the mean for individual cases was 16 (range 6.6-39.4). There was no observed difference between right, left, anterior, and posterior lung sections. There was a tendency for cases certified as sudden infant death syndrome to show lower macrophage counts than those with other causes of death, but the difference was of only marginal statistical significance. Seven of 10 cases in which infants died after a survival period in the hospital had a mean macrophage count greater than the overall mean of 16 per 40x field. These data suggest that mean pulmonary macrophage counts > 16 per 40x field may be a marker for causes of death other than sudden infant death syndrome or that there was a survival interval. These data may be useful as baseline data for further studies of infant mortality possibly involving pathologic changes in the lungs.
Insights
Pulmonary macrophage counts in infants may indicate cause of death. Higher counts (>16 per field) suggest causes other than sudden infant death syndrome or a survival interval.
Area of Science:
- Pulmonary pathology
- Infant mortality research
- Immunohistochemistry
Background:
- Macrophages play a role in lung immune responses.
- Understanding baseline pulmonary macrophage levels in infants is crucial for interpreting post-mortem findings.
- Previous studies have not established normative data for infant pulmonary macrophage counts.
Purpose of the Study:
- To establish baseline pulmonary macrophage counts in infant lung tissue.
- To investigate potential correlations between macrophage counts and cause of death or survival interval.
- To provide reference data for future infant mortality studies.
Main Methods:
- Prospective collection of infant lung autopsy samples from five US regions.
- HAM-56 immunostaining to identify macrophages.
- Independent counting of macrophages by three pathologists across standardized lung sections.
Main Results:
- Mean macrophage count was 16.5 per 40x field (range 0-136).
- No significant differences in counts based on lung section location (right/left, anterior/posterior).
- A trend towards lower counts in sudden infant death syndrome (SIDS) cases and higher counts in infants with a survival interval was observed.
Conclusions:
- Mean pulmonary macrophage counts exceeding 16 per 40x field may serve as a potential marker for non-SIDS causes of death or indicate a survival period.
- These findings provide valuable baseline data for infant lung pathology research.
- Further investigation is warranted to explore the clinical significance of these macrophage counts in infant mortality.
