Anticomplementary activity of equine whole IgG antivenoms: comparison of three fractionation protocols.

The research article focuses on reducing adverse reactions in patients treated with antivenoms using various fractionation methods. It specifically looks at anticomplementary activity (ACA) of equine whole IgG antivenoms produced by caprylic acid fractionation and compares three fractionation methods.

Overview of the Study

• The researchers explored the anticomplementary activity of equine whole IgG antivenoms. In understanding antivenom production, they ultimately aim to reduce early adverse reactions in patients treated with heterologous antivenoms that are commonly associated with anticomplementary activity.

Comparison of Fractionation Protocols

• The study compared three different antivenom processing, or fractionation procedures. The fractionation methods include routine caprylic acid fractionation; caprylic acid fractionation followed by beta-propiolactone treatment; and caprylic acid fractionation carried through ion-exchange chromatography using a quaternary ammonium membrane. These three methods were compared to determine if there were significant disparities in the ACA of the antivenom produced.

Outcome of the Fractionation Protocols

• Following the comparison, the three protocols showed reversed products with comparable physicochemical characteristics and anti-Bothrops asper venom antibody titers. Ion-exchange purified antivenom, however, had a lower protein concentration.
• Antivenoms fractionated using beta-propiolactone or filtration through a quaternary ammonium membrane demonstrated a significant reduction in in vitro ACA.

Impact of Changes to Antivenom Preparation

• As a part of the study, a preparation of caprylic acid-fractionated antivenom was heated to induce the formation of protein aggregates. Regardless, its ACA remained similar to the non-heated antivenom. The hemolytic activity of serum complement in rabbits remained unaffected after a bolus intravenous administration of any of the antivenoms.

Conclusion

• From the study, it was concluded that beta-propiolactone and quaternary ammonium membranes significantly decrease the in vitro ACA of caprylic acid-fractionated equine antivenom.
• Furthermore, the validity of in vitro ACA as a predictor of early adverse reactions should be reevaluated in clinical and experimental studies. In vitro ACA measurements may not accurately predict in vivo complement activation by antivenoms.