Setting Up an sST2 Immunoassay: Antigen, Antibody Pairs and Calibrators
A practical sequence for groups building an sST2 assay for the first time, from antigen format through to curve stability.
Antigen choice comes first
Recombinant antigen gives lot traceability and reproducibility; native material may be closer to the circulating form but is harder to source consistently. For calibrators, the decisive question is whether the format your antibody pair recognises is exposed — tagged versus carrier-free changes antibody accessibility.
Antibody pairing and matrix
The pair sets your linear range and sensitivity. On the calibrator side, carrier proteins such as BSA can introduce non-specific signal, which is the practical argument for carrier-free antigen in calibrator preparation.
Why lot consistency decides your curve
A drifting standard curve is more often traceable to antigen lot variation than to the antibodies. Re-validate a small side-by-side on each new lot and record the lot number with every curve.
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