Marine animal lectin-dependent tumor recognition by macrophages

Several lectins from marine animals, such as Balanus roseus hemagglutinin, B. balanoides hemagglutinin, Tetraclita squamosa japonica hemagglutinin and Aplysia kurodai agglutinin, were tested for induction of tumor lysis mediated by macrophages. Among them, B. roseus and B. balanoides lectins agglutinated several murine tumor cells and induced binding of macrophages to tumor cells. Binding of these cells was inhibited by galacturonic acid, suggesting that carbohydrate moieties on the cell membrane of the two types of cells are recognized by these lectins. These lectins did not induce tumor lysis in co-operation with various macrophages, but after inactivation of tumor cells with glutaraldehyde, they induced extensive lysis of target cells in the presence of macrophages. B. roseus lectin was also effective in vivo. These results suggest that tumor cells can be recognized via carbohydrate moieties on the cell membrane as well as tumor-associated antigen and that some animal lectins participate in macrophage-mediated cytolysis and tumor rejection.