ABSTRACT

Polyclonal anti-S react with Met²⁹ of red blood cell (RBC)-bound glycophorin B (GPB) but may also require adjacent amino acids. Treatment of RBCs with certain enzymes and sodium hypochlorite­-based bleach (NaClO) affect the interaction of GPB with anti-S. Some, but not all, anti-S react with hybrid glycophorin molecules associat­ed with the TSEN antigen. The purpose of this study was to charac­terize monoclonal anti-S and to compare their reactivity to polyclon­al anti-S in order to determine their potential as blood group reagents and research tools. Furthermore, through inhibition experiments, we attempted to define the epitope recognized by the antibodies.
Three monoclonal (MS-93; MS-94; MS-95) and two polyclonal (A1958; XI960) anti-S and a monoclonal anti-GPB (Mab 148) were tested by standard hemagglutination with RBCs of known common and rare phenotype, with S+ RBCs treated with enzymes, with dif­ferent concentrations of NaCIO, and after incubation with synthetic peptides. The anti-S gave different patterns of reactivity. Reactivity with sialidase-treated RBCs showed that MS-93, MS-95, Mab 148, and X1960 recognize sialic acid independent epitopes, whereas MS-94 and A1958 require sialic acid for optimal reactivity. MS-95 and X1960 were strongly reactive with TSEN+ RBCs and only Mab 148 agglutinated S- Dantu+ and S- St(a+) RBCs. MS-94 and Mab-148 agglutinated S+ RBCs treated with NaCIO. MS-93 was inhibited only by the 14-mer S-specific synthetic peptide whereas MS-95 was inhib­ited by all three synthetic peptides containing S-relevant residues.
This study clearly demonstrates that different anti-S have different characteristics that should be analyzed before selecting monoclonal antibodies for the basis of reagents for use in the clinical laboratory. These anti-S, because of their varied characteristics, wall be useful research tools.