Abstract

Background Inflammation is a key component of immune response to infections and pathogenesis of metabolic and cardiovascular diseases. Inflammatory biomarkers, including alpha-1-acid glycoprotein (AGP), are considered prognostic tools for predicting risk, monitoring response to therapy, and adjusting nutritional biomarkers for accurate interpretation. Serum is considered a primary source of biomarkers; urine and saliva are increasingly being explored and utilized as rapidly accessible, noninvasive biofluids requiring minimal sample processing and posing fewer biohazard risks.

Methods A lateral flow immunoassay was developed for an established mobile-based platform to quantify AGP in human serum, urine, and saliva. Assay performance was assessed with purified AGP in buffer, diluted human serum samples (n = 16) banked from a trial in people living with HIV, and saliva and urine (n = 15 each) from healthy participants. Reference methods were conventional clinical chemistry analyzer or commercial ELISA. Bootstrap analysis was used to train and validate sample calibration.

Findings The correlation between the assay and reference method for serum was 0.97 (P < 0.001). Mean (95% CI) best fit line slope was 1.0 (0.88, 1.15) and intercept was −0.003 (−0.08, 0.09). The correlation for urine was 0.93, and for saliva was 0.97 (both P < 0.001). The median CV for the LFIA for AGP in buffer was 13.2% and for all samples was 28.7%.