Effect of Gamma Radiation on the Structural and Functional Integrity of IgG

Abstract

Plasma-originated commercial intravenous immunoglobulin, which is used for a variety of clinical purposes, has been studied to determine the effect of virus-inactivating doses of gamma irradiation on the structural and functional characteristics of the protein. A detailed analysis has been performed in response to a concern that the use of conventional gamma irradiation may damage biologically active proteins. The results demonstrate that although gamma irradiation of the IgG may have some impact on protein structure, the damage can be reduced or even prevented by appropriate irradiation conditions. At the virucidal dose of gamma irradiation (50 kGy) and a temperature of −80oC, the integrity of the polypeptide chain of immunoglobulin and the secondary structure of IgG can be completely protected, while conformational changes in tertiary structure are significantly minimized to a level that preserves functional activity. The irradiated IgG retains specific antigen-binding properties and Fc-binding activity, indicating that the conformational integrity of the most important structural regions is not affected by gamma-irradiation. These results present strong evidence that gamma irradiation treatment can be effectively implemented for inactivation of pathogens in IgG solutions that are used for intravenous injection.