Human IgG subclass measurements in the clinical laboratory

Area of Science:

• Immunology
• Clinical Chemistry

Background:

• Human immunoglobulin G (IgG) subclasses exhibit distinct biological functions, including complement activation, receptor binding, and placental transfer.
• Early research utilized polyclonal antisera, while a 1985 IUIS/WHO panel established specific monoclonal antibodies for IgG subclass identification.
• Clinical assays employing monoclonal antibodies enable the quantification of IgG subclass concentrations and their distribution in immune responses.

Purpose of the Study:

• To provide a comprehensive overview of human IgG subclass properties relevant to clinical laboratory assays.
• To guide investigators in evaluating and developing quantitative IgG subclass assays.
• To summarize the clinical significance and applications of IgG subclass measurements.

Main Methods:

• Review of physical (structural) and biological (functional) properties of human IgG subclasses.
• Examination of HP-series monoclonal antibodies with documented specificities and their application in immunological methods.
• Discussion of technical aspects of total and antigen-specific IgG subclass immunoassays.

Main Results:

• Documented differences in complement activation, cell surface-receptor binding, blocking activity, and placental transfer among IgG subclasses.
• Availability of specific monoclonal antibodies for precise IgG subclass quantification.
• Development of clinical assays for measuring IgG subclass protein concentration and distribution.

Conclusions:

• Quantitative IgG subclass assays are vital tools for understanding human immune responses in health and disease.
• Knowledge of IgG subclass properties and assay methodologies is essential for clinical laboratory investigators.
• IgG subclass measurements have significant clinical applications in diagnosing and managing various health conditions.