Antibody quality and reliability

Our validation philosophy

IPI is committed to providing reliable, well-characterized protein reagents to the global research community. We understand that quality is not a single checkpoint and therefore apply rigorous quality control standards across every stage of recombinant antibody discovery, production and distribution.

Our approach aligns with well-established standards, while incorporating a unique focus on family cross-reactivity, target selectivity, data transparency and community-driven validation.

The IPI approach

Fundamental antibody quality

Test basic antibody quality, using size exclusion chromatography (SEC), mass spectrometry and polyspecificity reagent (PSR) assays.

Affinity & kinetics

Check antibody binding affinity and kinetics, using surface plasmon resonance (SPR) in vitro and flow cytometry in mammalian cells expressing exogenous antigen.

Family cross-reactivity

Assess cross-reactivity to related protein family members, using immunofluorescence (IF) assays designed for mammalian cells expressing exogenous antigen.

Physiological validation

Demonstrate activity in at least one additional application (IF, immunoprecipitation or immunohistochemistry), using cells or tissues that express endogenous antigen.

Our antibodies

IPI antibodies are biophysically-assessed, application-validated and distributed by our partner, Addgene, a nonprofit plasmid and antibody repository. We take a family approach to antibody production, developing suites of antibodies to whole protein families. This strategy allows us to test for cross-reactivity amongst closely related family members and ensure target selectivity.

With each purchase, researchers receive a full antibody profile, including data on antibody and antigen sequences, biophysical characteristics, cross-reactivity, target selectivity and assay performance. All validation results are available through our antibody collections and the Addgene Data Hub.

Our validation standards

Initial quality check

All purified recombinant antibody candidates undergo size exclusion chromatography (SEC) to ensure purity and lack of aggregation, mass spectrometry to confirm their identity, and polyspecificity reagent (PSR) assays to assess polyreactivity.

Surface Plasmon Resonance (SPR)*

We perform high-throughput SPR to assess whether antibodies bind their target in vitro, and quantify their binding with affinity (KD) and kinetic (on/off rate) value determinations.

Flow cytometry*

We assess whether antibodies bind the antigen presented in native form in a CHO cell model system and gain an estimate of antigen binding potency.

Immunofluorescence (IF)*

We use a transiently transfected Chinese Hamster Ovary (CHO) cell system with constructs that allow native-form cell-surface presentation and a standardized IF protocol to determine antibody binding at multiple concentrations.

Cross-reactivity testing*

We perform flow cytometry and IF in our CHO cell model system to check for cross-reactivity amongst closely related family members, similar proteins and species. Staining in antigen-expressing CHO cells and no staining in non-expressing cells gives strong evidence for the absence of cross-reactivity.

Immunofluorescence (IF) in physiologically relevant cells**

We run additional IF tests using mammalian cell lines expressing endogenous antigen, looking for staining that matches the established target antigen expression level to support our specificity analyses and demonstrate physiologically relevant binding.

Immunohistochemistry (IHC)**

We evaluate antibody performance in IHC using fixed tissue sections to determine target detection, localization and signal specificity in physiologically relevant contexts. Antibodies are assessed for expected staining patterns, with appropriate controls.

Immunoprecipitation (IP)**

We test antibodies for their ability to capture native target protein, providing functional validation of antibody-antigen interaction and supporting suitability for biochemical applications.

Knockout or knockdown testing

Where available, we use knockout or knockdown models to further confirm antibody binding and specificity. Loss or significant reduction of signal in antigen-depleted cells or tissues provides evidence of target-specific binding.

*Testing is performed in model systems using exogenously expressing mammalian cells.
**All commercial products have been validated in at least one of these assays.

Browse our commercial Antibody Collections

Our Antibody Collections house synthetic recombinant antibodies directed against axonal guidance receptors, synaptic proteins, epitope tags and other essential protein targets. Each IPI product undergoes stringent quality control and multi-tier validation to ensure affinity, specificity and reliability.

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Learn about our Community Access Antibody Program

Through our Community Access Antibody Program (CAAP), researchers working with underserved protein targets have access to characterized pre-release IPI antibodies. CAAP participants share antibody performance data, protocols and research approaches, and take part in target-oriented workshops to drive protein development.

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