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Splenic marginal-zone macrophages and marginal metallophils in rats and mice
Abstract:
The splenic macrophages of rats and mice were studied by light and fluorescence microscopy to determine their phagocytotic uptake of carbon and neutral polysaccharide (Fic-F), and their lysosomal enzyme activities. In rats, the large macrophages of the marginal zone (MZ) showed a moderate to strong acid phosphatase activity, and took up most of the Fic-F, even though they showed a weak phagocytotic activity to carbon particles. Red-pulp macrophages, however, ingested a large quantity of carbon particles, and are considered to be the major scavengers in the rat spleen. In contrast, the MZ macrophages in the mouse spleen were the major scavengers and showed a vigorous uptake of both carbon and Fic-F. In rats, the marginal metallophils (MM), located at the outer border of the periarterial lymphatic sheath and boundary between the MZ bridging channel and surrounding tissue, ingested Fic-F, whereas those located around the follicular area did not. In mice, on the other hand, the MM never ingested Fic-F. Lightly carbon-ladened small cells were constantly seen in the MZ of both rats and mice. They showed little acid phosphatase activity and did not ingest Fic-F. They were also present in the blood circulation.
Insights
Spleen macrophages in rats and mice exhibit distinct scavenger roles. Mouse marginal zone macrophages are key scavengers, while rat red-pulp macrophages primarily clear carbon particles.
Area of Science:
- Immunology
- Cell Biology
- Histology
Background:
- Macrophages in the spleen play crucial roles in immune surveillance and clearance.
- Understanding macrophage heterogeneity is vital for comprehending splenic functions.
Purpose of the Study:
- To investigate the phagocytic activity and lysosomal enzyme profiles of rat and mouse splenic macrophages.
- To differentiate the scavenger functions of various splenic macrophage populations.
Main Methods:
- Light and fluorescence microscopy were employed.
- Phagocytosis of carbon particles and neutral polysaccharide (Fic-F) was assessed.
- Lysosomal enzyme activities, specifically acid phosphatase, were analyzed.
Main Results:
- Rat marginal zone (MZ) macrophages showed high Fic-F uptake and acid phosphatase activity but low carbon uptake, unlike rat red-pulp macrophages which excelled at carbon clearance.
- Mouse MZ macrophages demonstrated vigorous uptake of both carbon and Fic-F, acting as major scavengers.
- Marginal metallophils (MM) in rats ingested Fic-F in specific locations, whereas mouse MM did not ingest Fic-F.
Conclusions:
- Splenic macrophage populations exhibit species-specific functional specialization in phagocytosis and scavenger activity.
- Distinct macrophage subsets within the spleen are tailored for clearing different types of particulate matter.