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Synthesis of nitrite and nitrate in murine macrophage cell lines
1Department of Applied Biological Sciences, Massachusetts Institute of Technology, Cambridge 02140.
Abstract:
Synthesis of nitrite (NO2-) and nitrate (NO3-) was studied in the macrophage cell lines RAW 264.7, WEHI-3, PU5-1.8, J774A.1, and P388D1 and compared to the synthesis by thioglycolate-elicited peritoneal macrophages from C3H/He and C3H/HeJ mice. Treatment with Escherichia coli lipopolysaccharide (LPS) induced NO2-/NO3- synthesis by all the cell lines except P388D1, which remained unresponsive at the highest LPS concentration (50 micrograms/ml). Recombinant murine gamma-interferon induced NO2-/NO3- synthesis in only two cell lines (PU5-1.8 and RAW 264.7), although it activated synthesis by C3H/He and C3H/HeJ macrophages. Dual signal treatments consisting of lymphokines or gamma-interferon plus LPS stimulated NO2-/NO3- synthesis by all five cell lines and each line showed enhanced synthesis as compared to that induced by any single stimulus. Heat-killed Bacillus Calmette-Guérin and purified mycobacterial protein derivative stimulated NO2-/NO3- synthesis in three of five cell lines, while dextran sulfate, zymosan, and the synthetic adjuvant muramyl dipeptide were ineffective. Nitrite represented 50-75% of the total NO2-/NO3- produced in all cases. The kinetics of LPS-induced NO2-/NO3- synthesis in J774A.1 and C3H/He macrophages were identical; a 6-h lag phase was followed by a 24- to 48-h period in which NO2- and NO3- were in a ratio of approximately 3:2 at all time points.
Insights
Macrophage cell lines and mouse macrophages synthesize nitrite and nitrate (NO2-/NO3-). Lipopolysaccharide (LPS) and gamma-interferon treatments differentially induced NO2-/NO3- synthesis, with dual stimulation proving most effective.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Nitrite (NO2-) and nitrate (NO3-) synthesis are critical immune responses mediated by macrophages.
- Understanding macrophage activation pathways is key to modulating immune responses.
Purpose of the Study:
- To investigate and compare NO2-/NO3- synthesis in various macrophage cell lines and primary macrophages.
- To evaluate the efficacy of different stimuli, including lipopolysaccharide (LPS), gamma-interferon, and other immune modulators, in inducing NO2-/NO3- production.
Main Methods:
- Utilized five macrophage cell lines (RAW 264.7, WEHI-3, PU5-1.8, J774A.1, P388D1) and primary macrophages from C3H/He and C3H/HeJ mice.
- Stimulated cells with Escherichia coli lipopolysaccharide (LPS), recombinant murine gamma-interferon, heat-killed Bacillus Calmette-Guérin, purified mycobacterial protein derivative, and other agents.
- Quantified NO2-/NO3- synthesis and analyzed kinetics and product ratios.
Main Results:
- LPS induced NO2-/NO3- synthesis in most cell lines, except P388D1. Gamma-interferon showed limited induction in cell lines but activated primary macrophages.
- Dual stimulation (lymphokines or gamma-interferon plus LPS) synergistically enhanced NO2-/NO3- synthesis across all cell lines.
- Nitrite constituted 50-75% of total NO2-/NO3- production; LPS-induced synthesis exhibited a 6-hour lag phase followed by sustained production.
Conclusions:
- Macrophage cell lines exhibit differential responses to immune stimuli regarding NO2-/NO3- synthesis.
- Combined LPS and gamma-interferon signaling pathways are potent inducers of NO2-/NO3- production in macrophages.
- The findings provide insights into macrophage activation mechanisms and potential therapeutic targets.
