D3.07 - Low inter-lot variability and high long-term stability of ready-to-use and room temperature-stable dry reagents for Basophil Activation Testing against peanut extracts

Standardization of Basophil Activation Testing (BAT) remains a major challenge for its integration in clinical studies. Variability between reagent lots and limited stability data are recognized as sources of analytical noise that may bias longitudinal interpretation, particularly in food allergy trials where repeated measures are required. Ready-to-use and room temperature-stable dry BAT tubes represent an attractive approach to reduce hands-on variability, but their long-term reproducibility has not been extensively evaluated yet.

This study aimed to evaluate inter-lot variability and long-term stability of ready-to-use dried BAT tubes containing peanut allergen, using repeated dose–response curves performed across multiple donors and multiple storage times.

Whole blood samples from 8 donors allergic to peanut were activated with serial dilutions of peanut extract prepared in dry, ready-to-use, BAT tubes. For each donor, BAT dose–response curves were generated in parallel with 8 independently manufactured but compositionally identical lots. In addition, each donor was tested at 8 different timepoints, enabling simultaneous assessment of lot-to-lot variability and long-term reagent stability. Basophil were identified as SS^lowCD45⁺CD3^-CRTH2⁺ and their activation was quantified based on CD63 and CD203c upregulation after stimulation. Coefficients of variation (CVs) were calculated for all curve parameters.

Across all donors, lots, and timepoints, dose-response curves were highly consistent. Despite a difference of 16 months over the different manufactured tubes, inter-lot variability was minimal, with CVs consistently low for maximal activation values. Repeated testing at distant timepoints on different donors confirmed the long-term stability of the dried-tube format and its ability to support reproducible activation curves even in highly responsive donors. No drift, degradation, or loss of potency was observed over the seven-year range of tube production and storage. 

This study demonstrates that ready-to-use dried BAT tubes provide excellent reproducibility across manufacturing lots and maintain low lot-to-lot variability over several years. These findings support their suitability for longitudinal clinical studies, minimizing analytical variability and reducing the risk of misinterpreting lot-related fluctuations as true biological changes. Standardized dried BAT formats may therefore facilitate broader adoption of BAT as a standardized and reliable functional biomarker in food allergy research.