Interaction of Concanavalin A with Rat Lymphocytes

Concanavalin A covalently bound to acrylic polymer particles (enzacryl AA), which cannot enter the cells, stimulated rat lymphocytes into DNA synthesis. Evidence was obtained that concanavalin A binds to the lymphocyte membrane specifically through its sugar‐binding sites. No nonspecific adsorption was found. The equilibrium constant found for the binding of concanavalin A to the cell was 12 μ−1 at 37°C and 3°−l at 0°C. No heterogeneity in the affinity of the binding sites was detected. The average maximum number of concanavalin A molecules (Mol. wt 108000) that could be bound was about 5 ×106 per cell. Optimum stimulation of DNA synthesis was obtained when about 5%, of the available sites on the cells were occupied by concanavalin A.