Detection of complement activation by counterimmunoelectrophoresis (CIE)

Area of Science:

• Immunology
• Biochemistry

Background:

• The complement system is crucial for innate immunity.
• Activation of the third component of complement (C3) is a central event in complement system activation.
• Detecting C3 activation is vital for diagnosing various immune-related diseases.

Purpose of the Study:

• To evaluate Counterimmunoelectrophoresis (CIE) as a sensitive method for detecting C3 activation.
• To compare the sensitivity of CIE with the traditional CH50 assay in identifying complement activation.
• To differentiate native C3 from C3 split products using CIE.

Main Methods:

• Counterimmunoelectrophoresis (CIE) was employed to analyze C3 and its split products.
• Serum samples were activated using aggregated human immunoglobulin (agg-IgG) or inulin.
• Electrophoretic mobility and immunochemical identification with specific antisera were used to characterize precipitin lines.

Main Results:

• CIE detected a distinct precipitin line for C3 split products (C3c and C3d) with an anodal mobility, separate from native C3.
• CIE identified C3 split products in patients with subnormal CH50 levels, indicating complement activation.
• CIE detected C3 split products earlier than a significant decrease in CH50 levels after complement activation.

Conclusions:

• CIE is a highly sensitive, specific, and rapid technique for detecting complement system activation via classical or alternative pathways.
• CIE can identify C3 split products even when C3 concentrations vary.
• This method offers a valuable diagnostic tool for complement-mediated diseases.