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Acute endotoxin-induced lymphocyte subset sequestration in sheep lungs
S S Duke1, M L Guerry-Force, J T Forbes
1Department of Medicine, Pathology and Oncology, Vanderbilt University, Nashville, Tennessee.
Summary
Endotoxemia in sheep reduces circulating T and B lymphocytes while increasing their accumulation in lung tissue. This suggests lymphocytes may play a role in endotoxin-induced lung injury and pulmonary hypertension.
Area of Science:
- Immunology
- Pulmonary Medicine
- Pathophysiology
Background:
- Endotoxemia triggers pulmonary hypertension and increased microvascular permeability.
- Physiological changes include leukopenia and leukocyte accumulation in the lung.
Purpose of the Study:
- To quantify lymphocyte subpopulations in blood, lung lymph, and lung tissue during endotoxemia in sheep.
- To investigate the role of lymphocyte migration in endotoxin-induced lung injury.
Main Methods:
- Sheep were infused with E. coli endotoxin or saline.
- Lymphocyte populations (T1, T4, T8, B cells) were identified using monoclonal antibodies and fluorescent labeling.
- Blood, lung lymph, and lung tissue samples were collected over 240 minutes.
- Pulmonary artery pressure and lung lymph flow were monitored.
Main Results:
- Endotoxin significantly reduced T and B lymphocytes in blood and lung lymph.
- Total leukocytes and granulocytes decreased in blood starting at 30 minutes.
- Lymphocyte counts in blood fell from 60 minutes, with all subsets contributing.
- Lung lymph showed reduced leukocytes (T1, T4, T8, B cells) from 120 minutes.
- Lung tissue revealed a significant increase in sequestered T lymphocytes.
Conclusions:
- Endotoxemia in sheep leads to lymphocyte depletion in circulation and accumulation in lung tissue.
- Lymphocyte sequestration in the lungs during endotoxemia may contribute to lung injury.
- These findings highlight the dynamic role of lymphocytes in acute lung inflammation.