Inhibition of ascites tumor development by concanavalin a

The protein concanavalin A (Con. A) that binds to glucose or mannose‐like sites on the cell surface membrane, and glycoproteins from wheat germ and soybean that bind to N‐acetyl‐D‐glucosamine‐like sites and N‐acetyl‐D‐galactosamine‐like sites, respectively, agglutinate cells of the ascites form of a Moloney virus‐induced lymphoma (YAC) grown in vivo. Although YAC cells were agglutinated by all three agglutinins, only Con. A showed a marked toxic effect on YAC cells in vitro and in vivo. In vitro incubation with 125μMg Con. A for 24 h lysed 95% of the cells. Intraperitoneal injection of 1 mg Con. A at 1 h, 2 days and 5 days after intraperitoneal inoculation of 10 2 YAC cells into adult mice, resulted in an inhibition of tumor formation in 70%, 50% and 20% of the animals, respectively. The results indicate that activities essential for cell survival are associated with Con. A sites, but that most of these activities are not associated with sites for the wheat germ and soybean agglutinins.