CSI2 Antibody

Collagen Type II (CII)-Specific Antibodies

CII-specific antibodies are critical in studying rheumatoid arthritis (RA) pathogenesis. Key epitopes include:

These antibodies demonstrate arthritogenic properties in collagen-induced arthritis models, with monoclonal antibodies (e.g., M2139, CIIC1) inducing acute arthritis in mice .

CSI-BLI: High-Throughput Antibody Self-Interaction Detection

Bio-layer interferometry (BLI)-based Clone Self-Interaction (CSI) assays enable rapid screening of antibody aggregation propensity:

• Throughput: 96 antibodies tested in 2 hours vs. days for chromatographic methods .

• Material Efficiency: Requires only 15 µg per antibody .

• Correlation: Strong agreement with size-exclusion chromatography (SIC) and cross-interaction chromatography (CIC) results (Fig. 1E in ).

Anti-CII Antibodies in Clinical Context

• Prevalence: 47% in RA sera vs. 77% in synovial fluid for U1 epitope .

• Pathogenicity: Antibodies against C1/U1/J1 epitopes disrupt cartilage via matrix protein interaction .

• Diagnostic Utility: Distinct from anti-citrullinated protein antibodies (ACPA), enabling RA subset stratification .

Technical Considerations for Antibody Detection

Monoclonal Antibody Production

CII-specific monoclonal antibodies (e.g., M2139, CIIC1) are generated via hybridoma technology and purified using γ-bind affinity chromatography . Key properties:

• Isotypes: IgG2a/IgG2b for optimal complement activation .

• Specificity: No cross-reactivity with non-collagen matrix proteins (e.g., fibronectin) .

Unresolved Questions

• CSI2 Definition: The term may refer to (a) a second-generation CII epitope-targeting antibody or (b) a procedural designation in CSI-BLI workflows.

• Clinical Translation: Anti-CII antibodies show therapeutic potential but require epitope-specific validation to avoid off-target effects .