Detection of Binding Activity of Antibody Drugs

The evaluation of binding activity of antibody drugs (such as monoclonal antibodies) is a key step in ensuring their efficacy and safety in the drug development and quality control process. Binding activity refers to the ability of an antibody to bind to its specific antigen. Here are some commonly used methods for evaluating the binding activity of antibody drugs:

 

1. Enzyme-Linked Immunosorbent Assay (ELISA)

ELISA is a common method that can quantify the binding ability of antibodies to antigens. The antigen is fixed on a microplate, the test antibody is added, and then a secondary antibody (against the test antibody) with enzyme labeling is used for detection. By measuring the enzyme's activity (usually through color change), the binding activity of the antibody can be indirectly quantified.

 

2. Surface Plasmon Resonance (SPR)

SPR technology can monitor the interaction between antibodies and antigens in real time. Antigens are usually fixed on a sensor chip, and when antibodies pass through, it causes changes in the optical signal, which can be used to determine parameters such as affinity (KD), binding rate (ka and kd).

 

3. Bio-Layer Interferometry (BLI)

Similar to SPR, BLI uses an optical sensor to monitor the binding of antibodies to antigens. BLI does not require a complex fluid system, simplifying the experimental process.

 

4. Competitive Binding Experiments

In these experiments, a labeled antibody with known affinity competes with the test antibody for binding to the antigen. By measuring the reduction in binding of the labeled antibody, the binding activity of the test antibody can be inferred.

 

5. Cell-Based Functional Tests

If the mechanism of the antibody drug involves targets on the surface of cells, cell experiments can be used to assess the binding of the antibody and its subsequent biological effects, such as ADCC (antibody-dependent cell-mediated cytotoxicity).

 

The choice of detection method is usually based on the type of information needed (such as quantitative or qualitative), the properties of the antibody, and the available experimental resources. ELISA and SPR are the two most common methods because of their high flexibility, applicability to most antibody drugs, and they can provide rich binding kinetics data.