Preparation and Evaluation of In-House Multi-Analyte Quality Control Materials for ANA, Anti-dsDNA, and Autoantibody Profile Assays

BACKGROUND: This study explored the preparation and evaluation of in-house quality control (QC) materials for antinuclear antibody (ANA) and anti-double-stranded DNA antibody (anti-dsDNA) testing by indirect immunofluorescence test (IIFT), and ANA profile testing by line immunoassay (LIA), with the aim of providing a reference for other in-house QC materials. METHODS: Patient sera were pooled to prepare a QC serum positive for all targets, while sera from healthy individuals were pooled to prepare a negative control. QC materials were heat-inactivated, centrifuged, aliquoted, and stored at -20 °C. Stability was assessed at 37 °C and during long-term storage at -20 °C. Inter-vial variation was evaluated using 20 vials, and intra-vial variation was assessed by 20 replicates of one vial. RESULTS: During the 8-day 37 °C stability test, ANA and anti-dsDNA titers remained within ± 1 serial dilution of the baseline value, and all ANA profile antibodies remained within the predefined ± 20% acceptance criterion. During long-term storage, ANA and anti-dsDNA titers also remained within ± 1 serial dilution, and the CVs of all ANA profile antibodies were below 20%. Both inter-vial and intra-vial variation met predefined criteria, and all negative controls remained negative. CONCLUSIONS: The in-house QC materials showed good stability and reproducibility, with simple preparation and potential suitability for routine use in primary healthcare laboratories.