Human-murine chimeric autoantibodies with high affinity and specificity for systemic sclerosis

Area of Science:

• Immunology
• Biotechnology
• Medical Diagnostics

Background:

• Scleroderma 70 (Scl-70) autoantibodies aid systemic sclerosis (SSc) diagnosis.
• Obtaining positive patient sera for anti-Scl-70 is challenging, necessitating alternative diagnostic references.

Purpose of the Study:

• To develop specific, sensitive, and readily available diagnostic tools for SSc.
• To generate high-affinity humanized antibodies against human Scl-70.

Main Methods:

• Screening of a murine-sourced single-chain variable fragment (scFv) library using phage display against human Scl-70.
• Construction and humanization of high-affinity scFv fragments.
• Analysis of physicochemical properties, 3D structure, and electrostatic potential of scFv fragments.

Main Results:

• Ten high-affinity scFv fragments were identified, with three (2A, 2AB, 2HD) selected for humanization.
• Humanized antibodies demonstrated lower half-maximal effective concentration (EC50) values than positive patient serum.
• High specificity for Scl-70 was confirmed in diagnostic immunoassays for antinuclear antibodies (ANA).
• Antibody 2A showed the highest affinity and specificity for Scl-70, despite lower expression levels.

Conclusions:

• Humanized antibodies targeting Scl-70 offer a promising foundation for enhanced SSc diagnostic strategies.
• The study highlights the potential of specific humanized antibodies for improving the sensitivity and accessibility of SSc diagnosis.