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Bimodal granulocyte transit time through the human lung demonstrated by deconvolution analysis
W Y Ussov1, A M Peters, M J Myers
1Department of Medicine, Hammersmith Hospital, London, U.K.
Respiratory Medicine
|February 2, 1999
Summary
Pulmonary granulocyte transit time is bimodal, with activated cells moving slower. This finding impacts understanding of the pulmonary vascular granulocyte pool and systemic inflammation.
Area of Science:
- Pulmonary circulation physiology
- Immunology
- Nuclear medicine imaging
Background:
- The lungs serve as a significant reservoir for granulocytes.
- Previous studies quantified red blood cell transit but not granulocyte transit time in the pulmonary vasculature.
Purpose of the Study:
- To quantify pulmonary vascular granulocyte transit time using deconvolution analysis.
- To compare granulocyte transit dynamics with previously established red blood cell transit times.
Main Methods:
- Granulocytes and red blood cells were labeled with Technetium-99m (Tc-99m).
- Granulocytes were complexed with hexamethylpropyleneamine oxime (HMPAO) for labeling.
- Deconvolution analysis was used to determine impulse response functions (IRFs) for both cell types.
Main Results:
- Red blood cell IRF was monoexponential with a median transit time of 4.3 seconds.
- Granulocyte IRF was biexponential in 19 of 22 subjects, particularly those with systemic inflammation.
- Slow component median transit times for granulocytes ranged from 120-138 seconds, correlating with shape change and mean transit time.
Conclusions:
- Pulmonary granulocyte transit is bimodal, with activated cells exhibiting slower transit.
- The proportion of slowly transiting cells is linked to mean transit time and influences the pulmonary vascular granulocyte pool size.
- Findings offer insights into granulocyte behavior in systemic inflammatory conditions.