The Evaluation Of The Antibody Diversity And The Fc Function Of Chinese Intravenous Immunoglobulins

Objective:To provide technical supports for further understanding of the product features and ensure the effectiveness of intravenous immunoglobulin(IVIG),we established a quality evaluation system for IVIG products,including the diversity of antibodies in IVIG and the detection methods of Fc function.And then the methods were used to analyze IVIG products from 7-9 different Chinese and 1 European plasma fractionation companies.Methods:1.Two-dimensional electrophoresis(2-DE)and protein immunoblotting were used to investigate diversity of antibody repertoire against Escherichia coli 0157:H7,some special spots were selected and identified by mass spectrometry after comparing the obtained antibody repertoires with 2-DE gels;2.The ability to activate complement of Fc fragment of IVIG were evaluated by hemolysis method,and the flow-cytometric method were used to evaluated the ability to bind Fc receptors of Fc fragment of IVIG;3.The IgG dimer level in IVIG were measured by high performance liquid chromatography(HPLC).Results:In this study,we have successfully developed the methods for evaluation of antibody repertoire and Fc function of IVIG.And then the IVIG preparations from different manufacturers were tested by these methods,the results are as follows:1.156±48 protein spots of E.coli were recognized by IVIG products of domestic eight manufacturers,while 124 spots were recognized by a foreign Octapharma IVIG preparation.Among 33 E.coli proteins analyzed by Mass spectrometry,29 proteins were unambiguously identified.And these proteins were highly conserved sharing homology with many pathogenic microorganisms;2.All IVIG samples were detected biological activity against human diphtheria toxoid and their Fc function indexs were more than 60%,but Fc function between different mannufacturers,IVIGs showed difference.When mannufacturer A was compared with the rest,we found F*>H*>G*>A>C>I>D*>E*>B*("*" means p<0.01);3.Fc binding activity varied across IVIG samples or different lots’IVIG from the same manufacturers.But all IVIG samples’ Fc binding activity were higher than 60%;compared with the A manufacturers,Fc function of some manufacturers’ IVIG showed significant difference;Conclusion:1.The evaluation systems can be used to analyze IVIG products’ diversity against theof pathogenic microorganisms and Fc function;2.Chinese IVIG products contain antibodies directed against a large range of epitopes shared by pathogenic microorganisms,and each IVIG preparation has its own distinct antibody repertoire;The Fc function of IVIG products was also different,and there were significant differences among some manufacturers,indicating that there may be differences in the clinical efficacy of commercial IVIG products;3.The establishment of a more comprehensive system for quality evaluation of plasma protein products contributed to in-depth analysis of product characteristics and instruction of clinical medication.