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Comparative biochemical and cytochemical studies on superoxide and peroxide in mouse macrophages
Abstract:
Maximal rates of superoxide (O-2) release, and the cytochemical locales of peroxide staining in resident, elicited, and activated macrophages have been determined. Macrophages elicited into the peritoneum with either casein (1.2% w/v) or proteose-peptone (10.0% w/v) release about twice as much O-2 as macrophages activated by infection of the animals with either Listeria monocytogenes, or Bacille Calmette-Guerin (BCG) followed by immune boosting with Purified Protein Derivative (PPD) (i.e., about 35 vs. 14-18 nmol O-2/min/10(7) cells). Macrophages elicited with thioglycollate (3.0% w/v) and resident macrophages produce negligible amounts of O-2 upon stimulation with PMA. These data are compared with those reported by other investigators who used different procedures. A cytochemical procedure for localizing peroxide has been modified for use with murine macrophages. No production of H2O2 by macrophages is detected cytochemically in the absence of stimulation. Upon exposure to PMA, resident macrophages are still largely unresponsive. Approximately 20% of the casein elicited macrophages and BCG-PPD activated macrophages exhibit H2O2 staining, which is largely restricted to the cytoplasmic vesicles and channels induced by PMA in these cells. The only exception to this staining pattern is a small population (about 2%) of activated macrophages which exhibits H2O2 staining in the cytoplasmic vesicles and channels and on the plasmalemma as well.
Insights
Activated macrophages release less superoxide (O-2) than casein-elicited macrophages. Peroxide (H2O2) staining in activated macrophages is localized, with a small percentage showing plasmalemma staining upon stimulation.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophages play a critical role in the immune response.
- Superoxide (O-2) and peroxide (H2O2) are key reactive oxygen species produced by macrophages.
- Understanding O-2 and H2O2 production varies with macrophage activation state.
Purpose of the Study:
- To quantify superoxide release rates in different murine macrophage populations.
- To determine the cytochemical localization of peroxide staining in these macrophages.
- To compare O-2 and H2O2 production across resident, elicited, and activated macrophage states.
Main Methods:
- Quantification of superoxide (O-2) release rates from macrophages.
- Cytochemical staining to localize peroxide (H2O2) production.
- Stimulation of macrophages with phorbol 12-myristate 13-acetate (PMA).
- Comparison of data with existing literature.
Main Results:
- Casein-elicited macrophages released significantly more O-2 (approx. 35 nmol/min/10(7) cells) than BCG-PPD activated macrophages (approx. 14-18 nmol/min/10(7) cells).
- Thioglycollate-elicited and resident macrophages produced negligible O-2 upon PMA stimulation.
- H2O2 staining was observed in ~20% of casein-elicited and BCG-PPD activated macrophages, primarily in PMA-induced cytoplasmic vesicles and channels.
- A small population (~2%) of activated macrophages showed H2O2 staining on the plasmalemma as well.
Conclusions:
- Macrophage activation status significantly influences superoxide release rates.
- Peroxide production is inducible by PMA and its localization differs between elicited and activated macrophages.
- Cytochemical localization provides insights into the cellular mechanisms of reactive oxygen species production in macrophages.