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Alternative pathways of sulfite oxidation in human polymorphonuclear leukocytes
D Constantin1, K Mehrotra, B Jernström
1Division of Toxicology, Karolinska Institutet, Stockholm, Sweden.
Pharmacology & Toxicology
|February 1, 1994
Summary
Human immune cells metabolize sodium sulfite via two pathways. One pathway, stimulated by oxidative bursts, involves sulfur trioxide anion radicals, while the other uses sulfite oxidase, whose activity varies among individuals.
Area of Science:
- Biochemistry
- Immunology
- Pharmacology
Background:
- Sodium sulfite metabolism in human polymorphonuclear leukocytes (PMNs) is not fully understood.
- Two distinct metabolic pathways for sodium sulfite have been proposed.
Purpose of the Study:
- To elucidate the metabolic pathways of sodium sulfite in human PMNs.
- To investigate the role of sulfite oxidase and oxidative burst in sodium sulfite metabolism.
Main Methods:
- Incubation of human PMNs with sodium sulfite.
- Measurement of sulfate formation.
- Stimulation of oxidative burst using phorbol myristate acetate.
- Assessment of sulfite oxidase activity.
Main Results:
- Sodium sulfite is metabolized via an enzymatic pathway (sulfite oxidase) and a non-enzymatic pathway (sulfur trioxide anion radicals).
- Phorbol myristate acetate-induced oxidative burst significantly enhances sulfate formation via the non-enzymatic pathway.
- Sulfite oxidase activity in PMNs exhibits considerable inter-individual variation.
Conclusions:
- Human PMNs utilize both enzymatic and non-enzymatic pathways for sodium sulfite metabolism.
- The non-enzymatic pathway is particularly sensitive to oxidative stress.
- Inter-individual variability in sulfite oxidase activity suggests a potential genetic polymorphism influencing sodium sulfite metabolism.