The immunochemistry of antibodies sharing concanavalin A's anti-mannosyl binding specificity

Procedures were developed for the synthesis of the disaccharide hapten, p-isothiocyanatophenyl 2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside, and for its conjugation to hemocyanin. The synthetic carbohydrate: protein antigen was then emulsified in complete Freund's adjuvant and injected into the footpads of New Zealand White rabbits. A population of the resulting anti-conjugate antibodies displayed some binding properties analogous to concanavalin A, the carbohydrate-binding protein of the jack bean. The antisera weakly percipitated mannans from Saccharomyces rouxii, S. cerevisiae, and an alpha-(1 leads to 3)-mannopyranosyl transferase-deficient mutant from Kluyveromyces lactis Y58a. These polysaccharides, possessing side chains containing terminal alpha-(1 leads to 2)-mannobiosyl residues, produce strong percipitation reactions with concanavalin A. In addition, various saccharides were tested for their ability to inhibit the interaction of anti-conjugate antisera with alpha-(1 leads to 2)-mannobiosyl-containing polymers. p-Nitrophenyl 2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside showed a strong complementarity for the binding sites of both the anti-conjugate antisera and concanavalin A. However, the antibody failed to bind a concanavalin A-reactive mouse fibrosarcoma or to stimulate mitogenesis of human peripheral lymphocytes.