Biological variation of soluble CD163

Area of Science:

• Biochemistry
• Immunology
• Clinical Chemistry

Background:

• A soluble plasma form of CD163 (sCD163) has been identified with anti-inflammatory properties.
• Elevated sCD163 levels are observed in patients with myelo-monocytic leukemia and infections.
• Understanding the biological variability and analytical quality of sCD163 assays is crucial for its clinical application.

Purpose of the Study:

• To investigate the day-to-day and diurnal biological variability of sCD163 in healthy individuals.
• To assess the analytical quality of a sandwich ELISA method for sCD163 measurement.
• To determine the suitability of sCD163 for monitoring individual patient status.

Main Methods:

• A sandwich ELISA was employed to measure sCD163 concentrations.
• 12 healthy individuals were studied to assess day-to-day and diurnal variations.
• Analytical coefficients of variation (CV) and biological variation components were calculated.

Main Results:

• The analytical CVs (within-run, between-run, total) were 3.6%, 4.8%, and 6.0%, respectively.
• Within-subject biological variation was 9.0%, and between-subject variation was 35.9%.
• A diurnal variation was observed, with 14% lower sCD163 levels at night; a low index of individuality (0.25) was found.

Conclusions:

• The analytical quality of the sCD163 assay is sufficient for clinical use.
• Significant biological variability necessitates careful interpretation of sCD163 levels, especially for monitoring.
• A critical difference of 30% is required to detect significant changes in serial sCD163 measurements for an individual.