Complement interaction with immune serum globulin and immune globulin intravenous

Area of Science:

• Immunology
• Biochemistry

Background:

• Intravenous immunoglobulin (IVIG) is used therapeutically, but its anticomplementary activity needs careful evaluation.
• Understanding the in vitro anticomplementary effects of modified IVIG preparations is crucial for safety and efficacy.

Purpose of the Study:

• To assess the in vitro anticomplementary activity of modified immune serum globulin (ISG) and immune globulin intravenous (IGIV).
• To compare the complement-activating potential of untreated and heat-aggregated IGIV and ISG.

Main Methods:

• Utilized three complement assays: C1q binding, C3 activation in normal human serum, and alternative pathway activity enhancement.
• Evaluated both untreated and heat-aggregated (63°C, 10 min) ISG and IGIV preparations.
• Quantified C1q binding affinity and C3 activation levels.

Main Results:

• Unheated IGIV showed marginal C3 activation and a fivefold lower affinity for C1q compared to ISG.
• Heat-aggregated IGIV was less effective in C3 activation and had a threefold lower C1q affinity than aggregated ISG.
• Both IGIV forms demonstrated significant enhancement of alternative pathway activity, similar to ISG.

Conclusions:

• Modified IGIV exhibits reduced in vitro anticomplementary activity compared to ISG.
• IGIV retains complement receptor activity, suggesting preserved efficacy in complement-mediated host defense.
• The lower capacity for nonspecific complement activation supports the safety of IGIV for intravenous administration.