Antigenic similarities both inside and outside the carbohydrate-binding sites of two-chain and one-chain leguminous lectins.
Antibodies were made against the two-chain lectin Lath-O from the seeds of Lathyrus odoratus as well as its isolated light (alpha) and heavy (beta) chains. These antibodies were used to antigenically compare the Lath-O with other two-chain lectins like Lath-S, lentil and Vicia cracca glc specific and with one-chain lectins like Con A, PHA, peanut and soybean. Sensitive ELISA tests showed that there was a distinct antigenic cross-reaction between the one-chain and two-chain lectins both by using antibodies against Lath-O whole molecules and its isolated beta-chains, while the anti-Lath-O alpha-chain antibodies barely reacted at all even with Lath-O alpha-chains. The antibodies against Lath-O whole molecules also strongly inhibited the mitogenic responses induced by two-chain lectins. Antibodies reacting inside the carbohydrate-binding site of the lectins were isolated by eluting them with glucose from lectin-Sepharose columns and antibodies reacting outside the carbohydrate-binding site were subsequently eluted with guanidine or buffer with low pH. The two antibody fractions were separately used to antigenically compare one-chain and two-chain lectins, demonstrating that both kinds of antibodies showed cross-reaction between one-chain and two-chain lectins. Both the antibodies presumably reacting inside the carbohydrate-binding site of the lectins and those reacting outside the carbohydrate-binding site inhibited haemagglutination activity of two-chain lectins, while haemagglutination by one-chain lectins was unaffected. The carbohydrate-binding site specificity of the glucose-eluted antibodies was assessed by glucose-inhibition in ELISA tests. Furthermore, galactose neither inhibited in these tests nor eluted antibodies from lectin-Sepharose columns. Control experiments were also performed with normal rabbit IgG.
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology; D000941:Antigens / Q000276:immunology*; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D003208:Concanavalin A / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D007887:Fabaceae; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007108:Immune Tolerance; D005779:Immunodiffusion; D037102:Lectins / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D008213:Lymphocyte Activation; D019887:Peanut Agglutinin; D010835:Phytohemagglutinins / Q000276:immunology; D037121:Plant Lectins; D010946:Plants, Medicinal; D011817:Rabbits
D000906:Antibodies; D000941:Antigens; D037102:Lectins; D019887:Peanut Agglutinin; D010835:Phytohemagglutinins; D037121:Plant Lectins; C033619:lentil lectin; D003208:Concanavalin A