Evaluation of immunoglobulin G preparations for anti-cytomegalovirus antibodies with reference to neutralizing antibody in the presence of complement.

Eighteen commercially available immunoglobulin G (IgG) preparations were evaluated by various methods for anti-cytomegalovirus (CMV) antibodies. The modifications of immunoglobulin G molecules, such as sulfonation, alkylation, and enzyme treatments, resulted in profound reductions in anti-CMV antibody titers. However, after reversion in vitro, sulfonated IgG preparations which have been shown to be reverted in vivo (Y. Masuho, K. Tomibe, K. Matsuzawa, T. Watanabe, S. Ishimoto, S. Tsunoda, and T. Noguchi, J. Biochem. 79:1377-1379, 1976) restored the anti-CMV antibody titers to levels comparable with those of nonsulfonated IgG preparations. There is no good correlation among the titers tested by different methods. As a method which reflects the biological activities in vivo, the neutralization test in the presence of complement is suitable for the evaluation of IgG preparations.