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Macrophage spreading disparity: alveolar vs peritoneal
D E Bechard1, B J Fisher, F K Kessler
1Departments of Medicine, Virginia Commonwealth University, Medical College of Virginia, Richmond 23298.
Abstract:
Macrophage spreading over glass surfaces is a recognized in vitro manifestation of activation. We examined macrophage spreading using a simplified assay. Hartley guinea pigs (n = 15) were anesthetized with pentobarbital (0.4 mg/gm) IM. Macrophages were obtained by lavaging the peritoneal (PM) and alveolar (AM) spaces with sterile 0.9% NaCl (NS). AM or PM (150,000 cells) were placed into chambers of Lab-Tek microtiter slides +/- phorbol myristate acetate (PMA). Slides were incubated /37 degrees C in 5% CO2 for 20 minutes. Macrophages with a diameter greater than 2 x control cells were considered spread. Compared to PM, resident AM show increased spontaneous spreading (16 +/- 2% vs 79 +/- 2%) respectively. AM demonstrated no significant concentration-dependent response to PMA stimulation. The PM has served as the basis for much of the morphological and functional observations attributed to macrophages in general. The above spreading data support the concept of disparity of macrophage function dependent upon various factors, including site of origin. Our observations suggest that extrapolation of macrophage characteristics to cells from discordant sources may not be possible.
Insights
Resident alveolar macrophages (AM) exhibit significantly higher spontaneous spreading than peritoneal macrophages (PM) in vitro. This highlights functional differences in macrophages based on their origin, suggesting caution when extrapolating findings.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophage spreading on surfaces is an indicator of in vitro activation.
- Peritoneal macrophages (PM) are commonly used to study macrophage behavior.
Purpose of the Study:
- To investigate and compare the in vitro spreading behavior of resident alveolar macrophages (AM) and peritoneal macrophages (PM).
- To assess the influence of phorbol myristate acetate (PMA) on macrophage spreading.
Main Methods:
- Hartley guinea pigs were used to obtain peritoneal and alveolar macrophages.
- Macrophages were cultured on microtiter slides and stimulated with or without PMA.
- Spreading was quantified by measuring cell diameter after incubation.
Main Results:
- Resident AM showed significantly higher spontaneous spreading (79% +/- 2%) compared to PM (16% +/- 2%).
- AM did not exhibit a significant concentration-dependent response to PMA stimulation.
Conclusions:
- Macrophage function, specifically spreading behavior, varies significantly based on their site of origin (alveolar vs. peritoneal).
- Findings suggest that characteristics observed in PM may not be universally applicable to all macrophage populations.