Blocking Antibody Screening Service

What Are Blocking Antibodies?

Blocking antibodies—also known as antagonistic or functional antibodies—are antibodies that inhibit a specific ligand–receptor interaction or signaling pathway. By preventing these interactions, blocking antibodies help determine:

  • The mechanism of action (MoA) of a therapeutic target
  • Whether an antibody candidate can interrupt functional binding events
  • The biological relevance of antibody–target engagement
  • The likelihood that a candidate may become a therapeutically effective antagonist

Blocking assays such as ELISA-based blocking, cell-based flow cytometry blocking, and SPR/BLI competition assays are therefore essential tools throughout antibody drug development—from early discovery and lead selection to functional validation.

Challenges in Blocking Antibody Screening

Despite being essential, blocking antibody screening is often difficult to establish internally:

  • Long development cycles: Building a stable, sensitive blocking assay can take weeks of optimization.
  • Poor reproducibility: Variability in ligand quality, antibody titration, or cell conditions often leads to inconsistent results.
  • Technical complexity: Each assay format requires specialized expertise and dedicated instruments.
  • High resource demand: Reagents, labor, and repeated optimization increase overall cost.
  • Lack of validated controls: Without reliable positive antibodies, confirming assay performance becomes challenging.

Why Choose DIMA BIOTECH's Service

To address these challenges, DIMA BIOTECH has established a comprehensive blocking antibody screening platform with multiple validated target-specific blocking assays, enabling rapid and reliable evaluation of functional antibodies.

  • Multiple Validated Blocking Assays Already Established
  • Multiple Analytical Formats Supported: ELISA or FC cell-based blocking assays
  • High Sensitivity & Reproducibility: Each assay is validated with well-characterized positive controls to ensure consistent performance.
  • High Throughput & Versatile Sample Types: Supports nanobodies, rabbit mAbs, human/mouse antibodies, bispecifics, and antibody libraries.

Service Workflow

1. Project Kick-off & Requirement Alignment

  • Clarify target biology & blocking model
  • Confirm screening workflow and deliverables
  • Ready for execution with no extra method development

2. Blocking Activity Screening

  • High-throughput competition assays
  • Measure % inhibition
  • Identify blocking hits

3. Blocking Curve Generation & IC50 Analysis

  • Dose–response testing of purified antibodies
  • Generate blocking curves (4PL fitting)
  • Determine IC50 & maximum inhibition

4. Functional Ranking & Final Data Report

  • Integrate potency + functional readouts
  • Rank candidates for development potential
  • Deliver full data package & recommendations

Case Studies

IL6R blocking ELISA assay

IL6R blocking ELISA assay

Competitive ELISA showing inhibition of IL-6R–ligand binding by a tocilizumab biosimilar. Serial antibody dilutions were incubated with IL-6R-hFc, followed by IL-6-mFc-His detection. The blocking curve yields an IC₅₀ of 35.11 ng/mL.

IL7RA Blocking ELISA assay

IL7RA Blocking ELISA assay

Competitive ELISA showing inhibition of IL-7RA–ligand binding by a Bempikibart biosimilar. Serial antibody dilutions were incubated with IL-7RA-hFc, followed by biotinylated lL7-hFc detection. The blocking curve yields an IC₅₀ of 25.96 ng/mL.

Successfully Developed Blocking Assays

Target Protein Reference Antibody Method
41BBL 41BB SC113.153 ELISA
ACVR2A Activin A bimagrumab ELISA
ACVR2B Activin A bimagrumab ELISA
Canine IL31 Canine IL31RA lokivetmab ELISA
Feline IL31 Feline IL31RA dovanvetmab ELISA
CD47 SIRPα magrolimab FACS
CSF1R M-CSF cabiralizumab ELISA
DLL3 Antibody epitope competition assay tarlatamab ELISA
EGFR EGF Cetuximab ELISA
HER3 NRG1 seribantumab
patritumab		 ELISA
IL21 IL21R avizakimab ELISA
IL21R IL21 IL21R BM ELISA
Target Protein Reference Antibody Method
IL31RA IL-31 nemolizumab ELISA
IL4RA IL4 dupilumab ELISA
IL6R IL6 tocilizumab ELISA
IL7RA IL7 bempikibart ELISA
IL7RA IL7 bempikibart FACS
MET HGF emibetuzumab ELISA
OX40 OX40L KH 72577-3 FACS
PD1 PDL1 pembrolizumab ELISA
Canine PD1 Canine PDL1 INTERVET 4F12 FACS
PDL1 PD1 atezolizumab FACS
TIGIT CD155 etigilimab FACS

FAQ

To support diverse research needs, antibody blocking assays can be developed using several analytical platforms, including ELISA blocking assays, flow cytometry–based blocking assays (FC), and biophysical competition assays such as SPR and BLI. Each method offers unique advantages for evaluating ligand–receptor interference, functional inhibition, and antibody mechanism-of-action.

Assay Platform Assay Principle What It Measures Strengths Typical Applications
ELISA Blocking Assay Measures competitive binding between antibody and ligand/receptor in a plate-based format % inhibition, IC50, maximal blocking rate Simple, scalable, high-throughput; ideal for early antibody screening Antibody–ligand blocking, surrogate neutralization assays, hit-to-lead functional evaluation
Flow Cytometry (FC) Blocking Assay Quantifies blocking by detecting ligand or antibody binding on cell surfaces Receptor occupancy, ligand-binding inhibition Physiologically relevant, cell-based context, high sensitivity Cell-based blocking assays, receptor occupancy analysis, functional antibody profiling
SPR Competition Assay Measures real-time competition between ligand, antibody, and target on a sensor surface Kinetics, blocking efficiency, binding mechanism Label-free, high-resolution kinetics, precise blocking evaluation Mechanism-of-action studies, affinity-driven blocking analysis, biophysical validation
BLI Blocking Assay Uses biosensor tips to quantify blocking in a real-time binding format Blocking efficiency, on/off rates, epitope-related effects Fast, flexible, multiplex-friendly High-throughput biophysical screening, epitope/competition studies, antibody panel selection