An enzyme immunoassay for urinary C-reactive protein

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Background:

• Urinary C-reactive protein (CRP) shows promise as a diagnostic biomarker.
• Existing methods for detecting urinary CRP may have limitations.
• Development of sensitive and reproducible assays is crucial for clinical application.

Purpose of the Study:

• To develop a sensitive enzyme immunoassay for quantifying urinary C-reactive protein (CRP).
• To validate the assay's reproducibility and correlation with established methods.
• To assess the applicability of the assay in clinical specimens.

Main Methods:

• Immobilization of anti-CRP antibody onto a plastic surface.
• Sequential addition of sample, biotinylated anti-CRP, enzyme-conjugated avidin, and substrate.
• Sample pretreatment using solvent exchange to mitigate assay inhibition by low pH or high urea.

Main Results:

• The developed enzyme immunoassay can detect as little as 0.5 ng of CRP.
• The assay demonstrated good reproducibility and strong correlation with radial immunodiffusion.
• Results from clinical specimens aligned with those from a complement fixation assay.

Conclusions:

• A sensitive and reproducible enzyme immunoassay for urinary CRP has been successfully developed.
• Sample pretreatment is necessary to overcome assay inhibition by urine composition.
• The assay is a viable tool for measuring urinary CRP in clinical settings.