Analytical validation of urine ALCAM ELISA as a test for lupus nephritis

Objectives: Urinary activated leukocyte cell adhesion molecule (uALCAM) is emerging as an outstanding biomarker for active lupus nephritis (ALN). This study aims to evaluate the analytic performance of the human ALCAM ELISA as an assay method to quantify uALCAM in patients with lupus nephritis. Methods: A commercially available human ALCAM ELISA kit was validated for its analytical performance as per Clinical & Laboratory Standards Institute guidelines. Results: Assaying 30 sets of serial dilutions of ALCAM exhibited an average CV of 10% and 97%–105% recovery. The assay also exhibited overall acceptable imprecision (CV < 20%) in day-to-day, site-to-site, and lot-to-lot reproducibility. The assay exhibited a reportable range from 4018 pg/ml down to 62 pg/ml with an r² of 0.999 in urine, with a limit of detection of 16–45 pg/ml. Most tested chemicals did not interfere with the assay, and no diurnal variations were observed in uALCAM levels. uALCAM was stable for at least 3 months at −20°C or −80°C. Conclusion: This analytic-validated uALCAM ELISA may provide physicians with an accurate and reliable tool for use in early detection of renal involvement in lupus, routine outpatient monitoring of disease activity, and long-term prognostication.