Evaluation of a research use only (RUO) TIMP-1 assay for use with the automated Alinity i platform

Tissue inhibitor of metalloproteinase-1 (TIMP-1) binds matrix metalloproteinases to regulate extracellular matrix turnover; elevated TIMP-1 has been associated with liver fibrosis, tumor progression, and fibrotic heart disease. We previously developed a quantitative, research use only (RUO) automated TIMP-1 immunoassay for use with the Abbott ARCHITECT i System; here, we describe the modification of the assay for use with the Abbott Alinity i system. The observed limit of detection was 1.42 ng/mL, and the calculated limit of quantitation was 2.44 ng/mL. In 100 normal plasma samples, TIMP-1 levels ranged from 106.23 ng/mL to 329.68 ng/mL. Deviation from linearity was ≤10% and precision was ≤10%CV across the analytical measuring interval from 2.44 to 500 ng/mL. No significant interference was observed for both conjugated and unconjugated bilirubin and hemoglobin at industry recommended test concentrations. Slight interference for protein and triglyceride resolved with titration to 12.15 g/dL and 750 mg/dL, respectively. Assay performance was optimal for plasma specimens in LiHep or EDTA. TIMP-1 in plasma samples was stable after multiple freeze-thaw cycles, up to 7 days at 2‒8 °C, and for up to 3 h on-board the Alinity i instrument. In cardiac plasma specimens, the assay consistently detected higher TIMP-1 in specimens with elevated troponin-I. The TIMP-1 immunoassay, modified for the Alinityi platform, detected TIMP-1 at physiologically relevant ranges. Future clinical development of the assay will focus on its clinical utility in various cardiac cohorts as a potential biomarker of fibrotic heart disease.