Circulating immune complexes in Behçet's syndrome: purification, characterization and cross-reactivity studies

Area of Science:

• Immunology
• Rheumatology
• Clinical Chemistry

Background:

• Behçet's syndrome is a complex inflammatory disorder.
• The presence and composition of circulating immune complexes (CICs) in Behçet's syndrome are not fully understood.

Purpose of the Study:

• To investigate the presence of CICs in patients with Behçet's syndrome.
• To characterize the components of purified CICs from these patients.

Main Methods:

• C1q-binding assay performed on 30 sera from Behçet's syndrome patients.
• Immunoadsorption using C1q-coated beads for CIC isolation and purification.
• Component analysis of purified CICs using double immunodiffusion and solid-phase radioimmunoassay.
• Radioiodination (125I) for labelling purified CICs.

Main Results:

• Circulating immune complexes were identified in 46% of patients with Behçet's syndrome.
• Purified CICs were found to contain immunoglobulin G (IgG), complement components C1q, C1s, and C3.
• Anti-IgG activity was undetectable in purified CICs.
• Specific cross-reactivity was observed in the majority of Behçet's syndrome sera using a solid-phase radioimmunoassay.

Conclusions:

• Circulating immune complexes are prevalent in Behçet's syndrome.
• These CICs are composed of IgG and early complement proteins (C1q, C1s, C3).
• The findings suggest a potential role for these immune complexes in the pathogenesis of Behçet's syndrome.