Chemotactic Activity of Lectins in vitro

The effects of concanavalin A (Con A) and leucoagglutinin (LA) on the locomotor response of phagocytes have been studied in vitro. At concentrations of 1 to 4 μg/ml, Con A and LA induced maximal chemokinesis and chemotaxis of monocytes, macrophages and, to a lesser degree, also of neutrophils. The lectin-induced locomotion was accompanied by membrane alterations and metabolic changes, as shown by an increase of the ³H-uridine uptake and a rise of the hexose monophosphate shunt activity. The chemotactic activity of Con A was inhibited by α-methyl mannoside (50 mM) or by pretreatment of the cells with trypsin. These data indicate that lectins such as Con A induce chemotaxis by a specific binding to receptors of the cell membrane. It is suggested that bivalent ligand binding is required as a signal to elicit chemotactic locomotion.