A novel general and efficient technique for dissociating antigen in circulating immune complexes.

Area of Science:

• Immunology
• Biochemistry

Background:

• Circulating immune complexes (CICs) are key indicators of immune response.
• Accurate detection of CIC-bound antigens is clinically significant for disease diagnosis.
• Existing methods for CIC dissociation and antigen detection have limitations.

Purpose of the Study:

• To develop a general and efficient buffer dissociation technique for separating CICs from serum.
• To improve the dissociation of antigens from CICs for enhanced detection.
• To validate the technique's efficacy across various CIC types.

Main Methods:

• Utilized polyethylene glycol (PEG) two-precipitation separation.
• Employed a glycine-HCl buffer system for dissociation.
• Compared the new technique with traditional PEG precipitation, HCl dissociation, trypsin digestion, and immune complex transfer.

Main Results:

• The PEG two-precipitation technique yielded higher measurement values than traditional PEG precipitation.
• Dissociation conditions varied slightly among different CICs (HCV Core-IC, HIV P24-IC, Ins-IC, TG-IC vs. HBsAg-IC).
• The new technique demonstrated superior antigen detection for HBsAg-IC, HCV Core-IC, HIV P24-IC, Ins-IC, and TG-IC compared to other methods.

Conclusions:

• The PEG two-precipitation dissociation technique offers improved separation and precipitation efficiency of CICs.
• This method minimizes macromolecular protein interference and free antigen adhesion.
• The technique is reliable, repeatable, valid, and applicable to samples with or without free antigens.