A Practical Workflow for Antigen-Antibody Pair Screening

A structured workflow for screening antibody pairs against a recombinant antigen, from coating controls to sandwich confirmation in the intended matrix.

Define the Assay Before Screening

Pair screening works best when the assay format is defined first. Decide the sample type, the required working range and the detection chemistry before testing antibodies, because these choices constrain which pairs can succeed. Establish a reference antigen preparation and keep it constant across the screen, so that differences in signal can be attributed to the antibodies rather than to the antigen. Changing the antigen mid-screen makes the resulting comparison meaningless. Plate the antigen at a fixed concentration and reserve it as a control across every plate in the run.

Stepwise Screening

Screen individual antibodies first as capture, using the reference antigen and a generic detection system, to rank binding and background. Then test candidate pairs in a sandwich format with the antigen in the intended matrix, applying each pair in both orientations because the results often differ. Include a no-antigen blank and a negative control on every plate. Rank pairs by signal-to-noise, dose response and consistency across replicates rather than by absolute signal, which varies with coating and detection conditions.

Confirming a Working Pair

A pair that performs in buffer should be re-tested in the intended sample matrix, where proteins and interfering substances can change the result. Check dilution linearity and recovery across the range, and confirm that the pair tolerates the sample handling you plan to specify. Examine performance at the ends of the curve, since a pair can appear sound at mid-range while failing at low concentrations. Record the orientation, the concentrations and the matrix for every pair you retain, so the selection can be reproduced.

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