Development and validation of an IL-6 immuno-receptor assay based on surface plasmon resonance

Area of Science:

• Biotechnology
• Immunology
• Analytical Chemistry

Background:

• Interleukin-6 (IL-6) is a key cytokine involved in immune responses.
• Assessing the biological activity and stability of recombinant IL-6 (rIL-6) is crucial for its therapeutic applications.
• Existing methods may not fully capture both immunological and biological integrity.

Purpose of the Study:

• To develop and validate a combined immunoassay and receptor-binding assay for rIL-6.
• To utilize Surface Plasmon Resonance (SPR) technology for high-precision analysis.
• To evaluate the stability of rIL-6 under various storage conditions.

Main Methods:

• Developed a dual SPR-based assay monitoring anti-IL-6 antibody/rIL-6 and rIL-6/IL-6 soluble Receptor (sIL-6R) interactions.
• Validated the immunoassay and receptor-binding assay for rIL-6 quantification and biological activity assessment.
• Assessed rIL-6 stability after storage at -70°C, -20°C, 5°C, and 25°C.

Main Results:

• The combined assay demonstrated high precision and recovery for both immunological and biological activity measurements (CVs < 1.7%, recovery > 98%).
• rIL-6 showed significant denaturation when stored at 25°C.
• No significant difference in rIL-6 integrity was observed between storage at -70°C, -20°C, and 5°C.

Conclusions:

• The validated SPR-based immunoassay and receptor-binding assay accurately characterizes rIL-6's immunological and biological integrity.
• The assay provides a sensitive and reproducible method for assessing rIL-6 stability.
• Optimal storage of rIL-6 is critical, with temperatures above 5°C leading to denaturation.