ANALYSIS OF THE ROLE OF TYPE-1 CORE O-GLYCANS IN THE BINDING OF ANTI-MUC1 ANTIBODIES BY CYTOFLUOROMETRY AND SYNTHETIC PEPTIDE GLYCOPEPTIDE BINDING-INHIBITION STUDIES/

A panel of 56 MAbs submitted to the ISOBM TD-4 (MUC1) Workshop were an alysed in two systems, These systems were designed to screen for pepti de type 1 core O-glycan-related reactivities, Using synthetic MUC1 muc in-related peptides and glycopeptides, the panel of MAbs were tested f or relative binding affinities to type 1 core O-glycan-substituted MUC 1 structures, These studies utilized a competitive binding format with a native human adenocarcinoma-derived mucin as a solid phase, This sy stem allows for analysis of the type 1 core glycoform subspecificity o f each MAb., The second approach taken in parallel, utilized MCF-7 (Br Ca) and OVCAR (OVCa) cell lines which were grown in the presence or ab sence of phenyl-N-acetylgalactosaminide (IF-gal), a blocker of mucin O -linked glycosylation. These cells were analysed by FAGS to examine th e role these same glycan substitutions play with regard to either the diagnostic or therapeutic application of these MAbs. By FAGS analysis there was a consistent increased 'epitope exposure' for peptide-specif ic MAbs binding in the presence of p-gal. In addition, a single MAb (T D-4 #150) is interpreted to react with a type 1 core O-glycan, probabl y with Tn, TF or STn specificity.