Preparation of human sera containing one single IgG subclass using affinity chromatography

Area of Science:

• Immunology
• Biochemistry
• Protein Chemistry

Background:

• Human immunoglobulin (Ig) subclasses play critical roles in the immune system.
• Obtaining purified individual IgG subclasses is essential for research and therapeutic applications.
• Existing purification methods can be time-consuming and may expose proteins to harsh conditions.

Purpose of the Study:

• To develop an efficient and gentle method for purifying human IgG subclasses from serum.
• To obtain serum preparations highly depleted of IgA, IgM, and specific IgG subclasses.
• To establish a reproducible protocol for isolating pure IgG1, IgG2, IgG3, or IgG4.

Main Methods:

• Immobilization of monoclonal antibodies against specific human IgG subclasses onto agarose beads.
• Use of coupled polyclonal anti-IgA and anti-IgM reactive gels.
• Application of negative affinity chromatography in a single or double run.
• Regeneration of columns for repetitive use.

Main Results:

• Serum preparations devoid of IgA, IgM, and all but one IgG subclass were successfully obtained.
• High purity was achieved in a single run for most IgG subclasses; IgG4 sometimes required a second step.
• The method uses mild conditions, avoiding high ionic strength, extreme pH, or chaotropic agents.
• Yields were approximately 50% (one run) to 20-30% (two runs).
• Columns demonstrated stability, withstanding up to 30 repetitive uses without significant activity loss.

Conclusions:

• A novel, easy, fast, and reproducible protocol for purifying human IgG subclasses was established.
• The method yields highly pure IgG preparations under mild conditions.
• This technique is suitable for obtaining specific IgG subclass preparations for research and potential clinical use.