 Solution

Antibody specificity requires comparison with alternatives. Measure binding to unrelated proteins and to appropriate related antigens under comparable conditions, with a reference surface controlling nonspecific sensor binding. Preferential binding to the intended target would support specificity within that tested panel.

Competition with a soluble target, or an independent interaction assay, can help establish that the signal reflects the intended interaction. Specificity for a particular epitope is a stronger claim than specificity for the target protein and needs evidence localizing the contact. A single good-looking binding curve establishes neither universal absence of cross-reactivity nor epitope identity.