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Quantifying Single Microvessel Permeability in Isolated Blood-perfused Rat Lung Preparation
Published on: June 30, 2014
Morphometric analysis of pulmonary intracapillary leukocyte pools in ex vivo-perfused rabbit lungs
L Ermert1, H R Duncker, S Rosseau
1Institute of Anatomy and Cytobiology, Justus-Liebig-University of Giessen, Germany.
Insights
Rabbit lungs contain large, slow-clearing pools of leukocytes in capillaries. These intracapillary leukocyte populations significantly influence lung immunity and inflammation, especially in isolated or transplanted lungs.
Area of Science:
- Immunology
- Pulmonary Medicine
- Cell Biology
Background:
- Understanding lung intracapillary leukocytes is crucial for studying immunological and inflammatory processes.
- Quantifying these cell populations aids in comprehending organ-specific immune responses.
Purpose of the Study:
- To develop and apply a computer-assisted method for quantifying lung intracapillary leukocytes in rabbits.
- To assess the kinetics and size of leukocyte pools within pulmonary capillaries during ex vivo lung perfusion.
Main Methods:
- Developed computer-assisted morphometry for digitalized electron-microscopic images.
- Analyzed buffer-perfused isolated rabbit lungs fixed at various time points (7.5, 35, 185 min) after artificial circulation onset.
- Compared data with nonperfused lungs (baseline) fixed by tracheal instillation.
Main Results:
- Significant pools of neutrophils, lymphocytes, and monocytes reside in rabbit pulmonary capillaries.
- Leukocyte counts in capillaries were higher than circulating cell pools.
- Cell volume and surface ratios remained constant during perfusion, indicating slow washout kinetics.
Conclusions:
- Rabbit pulmonary capillaries harbor substantial, slow-clearing leukocyte pools.
- These intracapillary leukocytes likely play a major role in immunological and inflammatory events in isolated-perfused and transplanted lungs.
Abstract:
Characterization and quantification of lung intracapillary leukocytes is of interest for a better understanding of immunological and inflammatory features in this organ. We developed a technique of computer-assisted measurement of digitalized electron-microscopic images and electronic data processing for morphometry of intracapillary leukocyte pools in rabbit lungs (L. Ermert, W. Seeger, and H.-R. Duncker, Cell Tissue Res. 271: 469-476, 1993). Measurements were undertaken in buffer-perfused isolated lungs (avoiding any reentry of washed-out cells); perfusion fixation was performed 7.5, 35, and 185 min after onset of artificial circulation (n = 5 each). Data were compared with that of nonperfused lungs fixed by tracheal instillation (baseline). Total lung capillary neutrophil counts were 1.41 x 10(9), 1.35 x 10(9), 1.37 x 10(9), and 0.69 x 10(9) (baseline, 7.5, 35, and 185 min perfusion, respectively). Corresponding data for intracapillary lymphocytes were 1.07 x 10(9), 0.84 x 10(9), 0.81 x 10(9), and 0.57 x 10(9); and for microvascular monocytes, data were 0.21 x 10(9), 0.19 x 10(9), 0.18 x 10(9), and 0.08 x 10(9). Ratios of cell volume and surface variables of the different intracapillary leukocyte types did not change during ex vivo lung perfusion. We conclude that the rabbit pulmonary capillary bed harbors large pools of different leukocytes, which surpass pool sizes of corresponding circulating cells and display very slow washout kinetics under conditions of lung-buffer perfusion. A major impact of these intracapillary leukocyte pools on immunological and inflammatory events in isolated-perfused and transplanted lungs must be assumed.
