Human Natural Antibodies Recognizing Glycan Gal?1-3GlcNAc (LeC).

ABSTRACT: The level of human natural antibodies of immunoglobulin M isotype against LeC in patients with breast cancer is lower than in healthy women. The epitope specificity of these antibodies has been characterized using a printed glycan array and enzyme-linked immunosorbent assay (ELISA), the antibodies being isolated from donors' blood using LeC-Sepharose (LeC is Gal?1-3GlcNAc?). The isolated antibodies recognize the disaccharide but do not bind to glycans terminated with LeC, which implies the impossibility of binding to regular glycoproteins of non-malignant cells. The avidity (as dissociation constant value) of antibodies probed with a multivalent disaccharide is 10-9 M; the nanomolar level indicates that the concentration is sufficient for physiological binding to the cognate antigen. Testing of several breast cancer cell lines showed the strongest binding to ZR 75-1. Interestingly, only 7% of the cells were positive in a monolayer with a low density, increasing up to 96% at highest density. The enhanced interaction (instead of the expected inhibition) of antibodies with ZR 75-1 cells in the presence of Gal?1-3GlcNAc? disaccharide, indicates that the target epitope of anti-LeC antibodies is a molecular pattern with a carbohydrate constituent rather than a glycan.

SUBMITTER: Dobrochaeva K 

PROVIDER: S-EPMC7554730 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature