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An electronmicroscopical study on peroxidase activity of rabbit monocytes, resident and exudate macrophages
Abstract:
Changes of peroxidase (PO) activity in blood monocytes, untreated or stimulated peritoneal macrophages and subcutaneous exudate macrophages of rabbits were investigated with the glucose-oxidase method in the culture experiments of these cells after their in vitro or in vivo adherence to the surface of foreign bodies. 1) PO activity was demonstrated in the nuclear envelope (NE) and rough endoplasmic reticulum (rER) in 75% of the untreated peritoneal macrophages. 2) Blood monocytes, most of the stimulated peritoneal macrophages, and subcutaneous exudate macrophages showed no PO positivity. 3) In the in vitro culture of blood monocytes and stimulated peritoneal macrophages, there appeared from 2 hours cells showing PO positivity in NE and rER. 4) Although blood monocytes, stimulated peritoneal macrophages, and subcutaneous exudate macrophages after their in vivo surface adherence showed no PO positivity, it appeared in these cells when further cultured in vitro. From the fact that such a positive change of PO activity in these cultured cells is not only a transient phenomenon but also in vitro cultural one, we cannot subscribe to the view that blood monocyte is the precursor of resident macrophages.
Insights
Peroxidase activity was observed in rabbit macrophages, but not in blood monocytes. In vitro culture induced peroxidase activity in monocytes and macrophages, challenging the idea that monocytes are precursors to resident macrophages.
Area of Science:
- Immunology
- Cell Biology
Background:
- Peroxidase (PO) activity is a key cellular enzyme.
- Understanding macrophage differentiation and function is crucial in immunology.
Purpose of the Study:
- To investigate peroxidase activity changes in rabbit blood monocytes and macrophages.
- To determine if blood monocytes are precursors to resident macrophages based on PO activity.
Main Methods:
- Glucose-oxidase method was used to measure PO activity.
- Cell cultures of blood monocytes, peritoneal macrophages, and exudate macrophages were performed.
- Cells were studied after in vitro and in vivo adherence to foreign bodies.
Main Results:
- PO activity was present in the nuclear envelope and rough endoplasmic reticulum of 75% of untreated peritoneal macrophages.
- Blood monocytes and most stimulated/exudate macrophages initially lacked PO activity.
- In vitro culture induced PO activity in blood monocytes and stimulated peritoneal macrophages within 2 hours.
- PO activity appeared in monocytes and macrophages after in vitro culture, even after in vivo adherence.
Conclusions:
- The induction of PO activity in vitro suggests a dynamic cellular response.
- The findings do not support the hypothesis that blood monocytes are direct precursors to resident macrophages.