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Appearance of peroxidase reactivity within the rough endoplasmic reticulum of blood monocytes after surface adherence
Abstract:
Rabbit blood monocytes, which contain no cytochemically demonstrable peroxidase, develop peroxidatic activity in the RER and perinuclear cisternae within 2 h after adherence to serum- or fibrin-coated surfaces. A similar reactivity appears in surface-adherent human and rat blood monocytes. In both localization and characteristics, this enzyme reactivity in monocytes resembles that normally seen in the resident peritoneal macrophages of the rabbit, as well as in several types of tissue macrophages in other species. Thus this observation supports the concept, presently based on the kinetic data of other investigators, that blood monocytes are the precursors of such cells. Moreover, the appearance of new enzyme activity after adherence may reflect alterations in cellular metabolism resulting from plasma membrane:surface interactions.
Insights
Rabbit blood monocytes gain peroxidase activity after adhering to surfaces, resembling macrophages. This suggests monocytes are precursors to macrophages, with adherence triggering metabolic changes.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Blood monocytes are immune cells with limited initial peroxidase activity.
- Macrophages, found in tissues, exhibit significant peroxidatic activity.
- Previous research suggested a monocyte-macrophage lineage based on kinetic data.
Purpose of the Study:
- To investigate the development of peroxidatic activity in blood monocytes upon adherence.
- To compare this induced activity with that of resident macrophages.
- To provide evidence for monocytes as precursors to macrophages.
Main Methods:
- Culturing rabbit, human, and rat blood monocytes on serum- or fibrin-coated surfaces.
- Assessing the development and localization of peroxidatic activity using cytochemistry.
- Comparing the enzyme reactivity in adherent monocytes with resident macrophages.
Main Results:
- Rabbit blood monocytes developed peroxidatic activity in the rough endoplasmic reticulum and perinuclear cisternae within 2 hours of adherence.
- Similar peroxidase activity was observed in surface-adherent human and rat monocytes.
- The induced enzyme activity in monocytes mirrored that of resident rabbit peritoneal macrophages and other tissue macrophages.
Conclusions:
- The study supports the hypothesis that blood monocytes are precursors to tissue macrophages.
- Adherence to surfaces induces new enzyme activity in monocytes.
- Plasma membrane:surface interactions likely trigger metabolic alterations in monocytes, leading to differentiation.