Measuring alveolar lavage fluid surfactant by fluorescence polarization

Area of Science:

• Pulmonary Medicine
• Biochemistry
• Analytical Chemistry

Background:

• Surfactant and albumin levels in bronchoalveolar fluid (BALF) are crucial indicators of lung health.
• Quantifying the surfactant/albumin ratio in BALF presents analytical challenges.
• Assessing surfactant status is particularly important in lung allografts.

Purpose of the Study:

• To develop and validate a method for quantifying surfactant/albumin ratios in BALF.
• To assess the utility of this method in differentiating between normal, transplanted, and native lungs.
• To provide a reliable tool for evaluating lung allograft status.

Main Methods:

• Bronchoalveolar fluid (BALF) samples were modified by adding albumin to bring surfactant/albumin ratios into the analytical range.
• Quantification was performed using the Abbott Laboratories TDx fluorescence polarization analyzer and fetal lung maturity reagents.
• Statistical analysis was used to compare ratios across different patient groups.

Main Results:

• The modified BALF assay demonstrated an analytical coefficient of variation (CV) of 2.9%.
• Significantly different surfactant/albumin ratios were observed between normal individuals, transplanted lungs, and contralateral native lungs (P = 0.006).
• A mathematical relationship allows conversion of modified ratios back to original sample ratios.

Conclusions:

• The described procedure provides a reliable method for quantifying surfactant/albumin ratios in BALF.
• This ratio is a valuable biomarker for assessing surfactant status, particularly in lung allografts.
• The method offers improved analytical performance and clinical utility for lung transplant monitoring.