Rheumatoid factor and its interference with cytokine measurements: problems and solutions

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Background:

• Cytokines are increasingly used as disease biomarkers.
• Immunoassays for cytokine detection can be affected by interfering antibodies, particularly rheumatoid factor (RF) in rheumatoid arthritis (RA) patients.
• RF is present in 65-80% of RA patients and can complicate diagnostic accuracy.

Purpose of the Study:

• To investigate the impact of RF on cytokine measurements in RA patient samples.
• To evaluate polyethylene glycol (PEG 6000) precipitation as a method to mitigate RF interference.
• To optimize cytokine analysis in RA patient plasma and synovial fluid.

Main Methods:

• Multiplex immunoassays (MIA) were used to quantify cytokines IL-1β, IL-4, IL-6, and IL-8.
• Samples from RA patients were analyzed before and after PEG 6000 precipitation.
• RF interference was assessed in both blood and synovial fluid samples.

Main Results:

• The presence of RF was confirmed to interfere with MIA cytokine measurements.
• PEG 6000 precipitation effectively eliminated RF interference in the analyzed samples.
• Accurate cytokine quantification was achieved after PEG precipitation.

Conclusions:

• RF interference is a significant issue in cytokine biomarker analysis for RA.
• PEG 6000 precipitation is a reliable method to remove RF interference.
• Recommended for all immunoassay measurements of plasma samples from RA patients to ensure accurate results.