Development of an offline noncompetitive flow immunoassay for the determination of interleukin-8 in cell samples

Area of Science:

• Biochemistry
• Analytical Chemistry
• Immunology

Background:

• Interleukin-8 (IL-8) is a critical cytokine involved in inflammatory responses.
• Accurate quantification of IL-8 in biological samples is essential for understanding disease mechanisms.
• Existing methods for IL-8 detection may require complex sample preparation or lack sensitivity.

Purpose of the Study:

• To develop and optimize a noncompetitive flow immunoassay (FIA) system for sensitive IL-8 detection.
• To compare the performance of different fluorescent labels (FLUOS and Cy5.5) and an enzyme label for IL-8 analysis.
• To validate the FIA system for IL-8 quantification in cell samples.

Main Methods:

• Development of a noncompetitive FIA system utilizing offline incubation and immunoaffinity column trapping.
• Conjugation of IL-8 antibodies with FLUOS and Cy5.5 fluorophores and horseradish peroxidase enzyme.
• Optimization of assay parameters including pH, antibody concentration, flow rate, and incubation times.
• Detection of immunocomplexes using fluorescence or enzyme substrate reactions.
• Identification of IL-8 in cell samples using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

Main Results:

• The FIA system demonstrated sensitive detection limits: 200 amol with FLUOS-labeled anti-IL-8 and 1 fmol with Cy5.5-labeled anti-IL-8.
• Optimization of assay conditions (pH, antibody concentration, flow rate, association time) improved assay performance.
• Successful application of the developed FIA technique for analyzing IL-8 in cell samples.
• MALDI-TOF MS confirmed the presence of IL-8 in the analyzed cell samples.

Conclusions:

• The developed noncompetitive FIA system provides a sensitive and efficient method for IL-8 analysis in cell samples.
• The system's performance can be tuned by optimizing fluorescent labels and assay parameters.
• This FIA technique holds promise for advancing research in inflammation and immunology through accurate IL-8 quantification.