Effect of C2-Associated Carbohydrate Structure on Ig Effector Function: Studies with Chimeric Mouse-Human IgG1 Antibodies in Glycosylation Mutants of Chinese Hamster Ovary Cells

摘要: The complex biantennary oligosaccharide at Asn297 of IgG is essential for some effector functions. To investigate the effect carbohydrate structure on Ab function, we have now expressed mouse-human chimeric IgG1 Abs in Chinese hamster ovary (CHO) cells with defined defects biosynthesis. We had previously shown that produced cell line Lec 1, which attaches a high-mannose intermediate carbohydrate, were severely deficient complement activation, showed slightly reduced affinity FcγRI, and vivo half-life. extended these studies by producing same dansyl-specific lines attachment sialic acid (Lec 2) galactose 8). IgG1-Lec 2, 8 all varying reactivity mAb specific an epitope amino terminal region CH2, suggesting conformations proteins altered different structures. Functionally, 2 comparable to wild type respect half-life, capacity complement-mediated hemolysis. While was essentially identical its interact individual components classical activation pathway, demonstrated equivalent maximal binding lower concentrations preferentially bound mannose-binding protein. Although 1 it superior activate alternative pathway. These demonstrate bearing CH2-linked differing structures functional properties.