Demonstration of the IgG antibody repertoire against the bacteria Escherichia coli in Chinese intravenous immunoglobulins.

Intravenous immunoglobulin (IVIg) is produced by pooling plasma from thousands of healthy blood donors, and the diversity of the antibody is critical for the clinical efficacy of IVIg. This study investigated the antibody diversity of Chinese IVIg. Firstly, 2-dimensional gel electrophoresis and immunoblotting with protein extracts of Escherichia coli (E. coli) O157:H7 were used to study IgG antibody repertoire of 8 IVIg preparations from different Chinese manufacturers. This was followed by the identification of the antibody-reactive proteins of E. coli by mass spectrometry and the sequence similarity of the proteins was aligned by bioinformatics analysis. The results showed that all IVIg preparations expressed a large range of antibody reactivities against E. coli proteins. 94-238 antigens were recognized by the 8 IVIg preparations. 33 interesting target antigens were selected and identified as 29 different proteins, mainly including membrane proteins, molecular chaperones, metabolism enzymes, and proteins involved in cell cycle processes. Additionally, these antigens were highly conserved proteins which were found extensively in a variety of other pathogenic microorganisms. Our study indicated that Chinese IVIg preparations recognized a large range of high conserved proteins which play key roles in pathogenic microorganisms, and showed each IVIg had its own distinct antibody repertoire.