Comparison Between Therapeutic Antitoxin F(ab)₂ Fractionated with Ammonium Sulfate and Caprylic Acid

Abstract

To date, animal derived therapeutic antibodies represent the best and only choice source of antitoxins, especially in developing countries. Furthermore, this industry needs to develop a production protocol to achieve safer products. Recently, several laboratories changed their production protocol from ammonium sulfate (AS) protocol to caprylic acid (CA) fractionation. Our results showed that using the CA protocol leads to improvement in the product quality, as assessed by the albumin and protein content decrease (from 4.75 to 3.54 g/dL and 0.64 to 0.18 g/dL, respectively), which yielded a purer antitoxin product. The F(ab)₂ protein aggregate formation and turbidity have been significantly reduced, 4.60 versus 2.55 and 0.046 versus 0.021 (p<0.01), respectively. However, the anti‐complementary activity was also reduced, from 42 to 33. The total IgG content was higher in CA fractionated products than AS materials. The endotoxin content was worrisome in some F(ab)₂ products.

Keywords:

• Horse F(ab)₂ antibody
• Fractionation protocols
• Ammonium sulfate
• Caprylic Acid
• Impurities
• Anti complementary

Acknowledgments

I wish to thank Mr. H. Abd Elkader and W. Wazier for technical assistance. This study was partially funded by grants from the (WHO/EMRO/COMSTECH‐04/13, and Egypt/USA JF No.65 for E.M.R.). The author thanks Dr. M. Kelker for language corrections and for his suggestions.