Publication Date:
2013-05-03
Description:
Assays for quantification, and methods for removal, of anti-A and anti-B antibodies are the key for the success of ABO incompatible organ transplantation programs. In order to produce tools that can be used as substrates in tests for anti-A/anti-B quantification and specificity determination or as affinity matrices in extracorporeal immunoadsorption (IA) columns, we engineered Chinese hamster ovary (CHO) cells secreting mucin-type fusion proteins carrying blood group A or B determinants on defined O -glycan core saccharide chains. Besides the P-selectin glycoprotein ligand-1/mouse immunoglobulin G 2b (PSGL-1/mIgG 2b ) cDNA, CHO cells were transfected with plasmids encoding core 2 (β1,6GlcNAc-T1) or core 3 (β1,3GlcNAc-T6 and β1,3Gal-T5) enzymes together with α1,2Fuc-T1 or α1,2Fuc-T2 and the A or B gene-encoded α1,3GalNAcT or α1,3Gal-T, respectively. Selected clones with the correct glycophenotype were expanded and cultured in shaker flasks and Wave bioreactors. Western blotting was used to characterize purified fusion protein and liquid chromatography–mass spectrometry was used to characterize the released O -glycans. Clones producing PSGL-1/mIgG 2b carrying O -glycans with A and B determinants on type 1 (Galβ3GlcNAc), type 2 (Galβ4GlcNAc) and type 3 (Galβ3GalNAcα) outer core saccharide chains were established. The conversion of CHO cells from exclusive inner core 1 (Galβ3GalNAc) to core 3 (GlcNAcβ3GalNAc) O -glycan producers was almost complete, whereas conversion to inner core 2 (GlcNAcβ6GalNAc) O -glycans was incomplete as was the α2-fucosylation of the core 1 chain. Sialylation may prevent these biosynthetic steps. The clinical utility of the blood group A and B substituted mucin-type fusion proteins as substrates in enzyme-linked immunosorbent assay or as affinity matrices in IA columns is explored.
Print ISSN:
0959-6658
Electronic ISSN:
1460-2423
Topics:
Biology
,
Medicine
Permalink