Catalogue Number, Meet Knockout: The Antibody Due-Diligence Walkthrough

The quiet cost of a confident label

Antibody reagents have a brilliant trick: they look validated. The datasheet has a neat band, a tidy immunofluorescence image and a sentence claiming “specificity verified”. The vial arrives with a catalogue number, a lot number and a small strip of hope. Then it sits in a freezer until a student needs a figure, at which point everyone discovers that hope is not a control.

In UK labs, this is a familiar reproducibility trap. Small groups inherit “the antibody that works” from a former postdoc. Shared cores stock antibodies with handwritten labels. Students order replacements from a catalogue number alone because the paper they are following used the same clone, or something close enough after a quick search. None of this is malicious. It is just what happens when reagent provenance is treated as admin rather than evidence.

In 2026, the expectations are tighter. Journals, funders and institutions increasingly ask for reagent identifiers, and the UK Reproducibility Network has spent years nudging labs towards better reporting. But the freezer door still closes on a lot of undocumented vials. The fix is not a heroic validation project. It is a short, repeatable due-diligence routine.

Start with identity, not sensitivity

The first question is not “does it work?” It is “what is it?” A catalogue number identifies a product, not a batch, and it certainly does not prove that the antibody in your hand binds the target you care about.

This is where RRIDs come in. A Research Resource Identifier is a stable label, usually from the Antibody Registry, that follows a reagent across papers, protocols and freezer maps. Put the RRID in your electronic lab notebook, your methods section and your internal antibody database. If a vendor does not list one, ask. If a colleague has a validated aliquot, record its RRID before you accept it. The useful UK search tools include CiteAb, which is based in Bath and tracks antibody citations, but citation counts are popularity data, not validation data. They tell you who has used a reagent, not whether it behaved.

Record the boring stuff too: host species, clonality, target epitope, conjugate, storage conditions and expiry date. A vial with no lot history is not a reagent; it is an anonymous liquid in a plastic tube.

What actually counts as validation?

Validation is a control problem, not a vibes problem. The gold standard, when it exists, is a knockout. If you have a CRISPR knockout cell line or tissue with confirmed loss of the target, run the antibody alongside the wild-type sample. A clean knockout lane is worth more than a hundred glowing vendor thumbnails.

Knockdown can help, but it is weaker. siRNA or shRNA experiments often leave residual protein, and the antibody may still detect something. Orthogonal evidence matters: if you use western blot, confirm with immunofluorescence, flow cytometry or immunoprecipitation. If the antibody is for a phospho-epitope, phosphatase treatment is a sensible control. For immunohistochemistry, use tissue with known expression and a matched negative tissue. For flow cytometry, include fluorescence-minus-one controls and, where possible, a knockout or knockdown sample.

UK core facilities are underused for this. Microscopy cores can help with imaging settings and controls; flow cores can advise on compensation and gating; proteomics facilities can run immunoprecipitation-mass spectrometry to check what the antibody actually pulls down. Ask before you spend weeks optimising a bad reagent. A short conversation with a core manager is often cheaper than a failed figure panel.

Lot-to-lot is version control for the freezer

Antibody lots vary. This is not a conspiracy; it is biology, manufacturing and QC. A new lot can behave differently from the one that produced last year’s beautiful blot. Treat each lot as a new reagent.

When a fresh lot arrives, retain a small aliquot of the old lot if you can. Run the new lot and the old lot side by side on the same gel or slide. Record the lot number next to every figure. Do not mix lots in a single experiment. Do not assume that “same catalogue number” means “same reagent”. Freeze-thaw gently, store at the temperature on the datasheet, and label aliquots with date, owner, RRID and lot. UK lab space is tight, but freezer archaeology costs more time than a roll of labels.

The five-minute purchasing pause

Before a vial enters the freezer, ask a few blunt questions:

• Is there an RRID, and is it recorded in our system?
• Has the vendor or another lab validated it in the species and application we need?
• What control data exist, and are they lot-specific?
• Is there a knockout or knockdown sample we can access?
• Can we buy a trial size before committing to a full vial?
• Does a UK core facility or neighbouring lab already have a validated aliquot?
• Who will own the validation record, and where will it live?

If the answer to most of these is “not sure”, the correct next step is not a purchase order. It is a search for evidence.

The pre-figure gate

Before an antibody result becomes a figure, do a final check. Methods section: RRID and lot. Images: acquisition settings, scale bars and controls. Quantification: independent replicates and raw data. Controls: knockout, knockdown or orthogonal assay. Lab notebook: who validated it, when and how. This is not bureaucracy for its own sake. It is the difference between a result and a rumour.

Antibodies are expensive, but bad antibodies are more expensive. They consume students, freeze time and generate figures that cannot be repeated. The vial is not the validation. The validation is the control you ran, the identifier you recorded and the questions you asked before the freezer door closed.