Nitric oxide production by human peripheral blood polymorphonuclear leucocytes

Area of Science:

• Immunology
• Biochemistry
• Clinical Chemistry

Background:

• Nitric oxide (NO) plays a crucial role in various physiological and pathological processes.
• Assessing NO release in clinical settings is challenging due to limitations in current methodologies.

Purpose of the Study:

• To develop and validate a rapid and reliable technique for measuring basal and stimulated nitric oxide release from human polymorphonuclear leucocytes (PMNs).
• To evaluate the impact of various stimuli and inhibitors on NO production in PMNs.

Main Methods:

• Isolation of peripheral blood PMNs using a single-step density gradient procedure.
• Quantification of NO release based on the conversion of oxyhaemoglobin to methaemoglobin.
• Stimulation of PMNs with phorbol myristate acetate (PMA), N-formyl-methionyl-leucylphenylalanine (fMLP), and preincubation with cytokines (LPS, IL-6, IFN-γ).
• Assessment of NO production inhibition using NG-monomethyl-L-arginine (L-NMMA) and L-canavanine sulphate.

Main Results:

• Established basal nitric oxide release from unstimulated PMNs (mean 283 +/- 96.7 pmol min-1 10(-6) cells), augmented by superoxide dismutase.
• Demonstrated increased NO release upon stimulation with PMA and fMLP.
• Showed enhanced NO production following preincubation with lipopolysaccharide (LPS), interleukin-6 (IL-6), and interferon-gamma (IFN-γ).
• Confirmed inhibition of NO production by L-NMMA and L-canavanine sulphate.

Conclusions:

• The described assay is a rapid, reliable, and valuable tool for assessing nitric oxide release in clinical situations.
• This method allows for monitoring nitric oxide up-regulation and cellular responses to various stimuli in a clinical context.