Development and pilot validation of a chemiluminescence immunoassay for monitoring immunologic changes during peanut oral immunotherapy using sIgE/sIgG4 ratio.

Abstract

Background: The sIgE/sIgG4 ratio has been proposed as a dynamic measure of immune modulation during peanut oral immunotherapy (OIT). This study evaluated a chemiluminescent immunoassay for simultaneous quantification of peanut-specific sIgE and sIgG4 on the automated Autolumo A2000 Plus platform.

Methods: Analytical performance was assessed for peanut, Ara h 2, and Ara h 6 sIgE and sIgG4. Method comparison with ImmunoCAP was performed across the measurable concentration range. In a separate retrospective pilot cohort of 23 peanut-allergic patients undergoing OIT, longitudinal sIgE, sIgG4 and sIgE/sIgG4 ratio trajectories were compared between A2000 and ImmunoCAP. Associations between ratio trajectories and OIT dose escalation were evaluated as an exploratory treatment-progression measure.

Results: The A2000 Plus demonstrated high analytical sensitivity (sIgE LOQ < 0.05 kU/L; sIgG4 LOQ < 0.06 mg/L), precision (intra- and inter-assay CVs < 3% and <5%, respectively), and linearity (R² > 0.990). Method comparison with ImmunoCAP showed high positive percent agreement (82%-97%) and negative percent agreement (92%-100%), with strong concordance for log(sIgE) (ρ = 0.9041), and log(sIgG4) (ρ = 0.8464). Longitudinal analysis showed increased sIgG4 levels and decreased sIgE/sIgG4 ratio over time (p < 0.001), paralleling OIT dose escalation. Log(sIgE/sIgG4) ratio trajectories were strongly concordant between platforms across peanut, Ara h 2 and Ara h 6 (ρ = 0.900-0.917).

Conclusion: The Autolumo A2000 Plus demonstrated strong analytical performance and captured expected immunologic trends during peanut OIT. These findings support further investigation of this platform as a potential complementary monitoring tool in OIT. Larger prospective studies are required to establish clinical utility.