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Human IgG is a well-established multifunctional antigen-specific immunoglobulin molecule of the adaptive immune system.However, an antigen nonspecific immunological function of human IgG has never been reported.In this study, human IgG was isolated using ammonium sulfate fractional precipitation and diethylaminoethanol (DEAE) cellulose ion exchange chromatography, from which h-IgGand hs-IgG fractions were purified on the basis of their differential binding to rabbit anti-shrimp hemocyanin antibody(h) and rabbit anti-shrimp hemocyanins small subunit antibody(hs), respectively.We found that h-IgG had a higher hemolytic activity than hs-IgGagainst erythrocytes from humans, rabbits, mice and chicken, whereas the control IgG showed negligible activity.h-IgGcould interact directly with erythrocyte membranes, and this interaction was suppressed by high molecular weight osmoprotectants, showing that it may follow a colloid-osmotic mechanism.In comparative proteomics and glycomics studies, h-IgGand hs-IgG yielded 20 and 5 significantly altered protein spots, respectively, on a 2-D gel.The mean carbohydrate content of h-IgGandhs-IgG was approximately 3.6-and 2-fold higher than that of IgG,respectively, and the α-D-mannose/α-D-glucose content was in the order of h-IgG>hs-IgG> IgG.In this study,a novel antigen nonspecific immune property of human IgG was investigated, and the diversity in the protein constituents and glycosylation levels may have functional signficance.