The status of concanavalin A receptors on the lymphocytes of leukemic AKR mice: inhibition of redistribution by high concentrations of the lectin.

Cell-electrophoretic and fluorescence microscopic investigations were carried out on the interaction of concanavalin A with the splenic lymphocytes of normal and spontaneously leukemic AKR mice. The normal splenic lymphocytes (NSL) showed a biphasic profile of electrophoretic mobility (EPM) as a function of the concentration of Con A, under capping conditions. The mean EPM of NSL increased at low concentrations of the lectin and was reduced below that of untreated cells at higher (greater than or equal to 15 micrograms/ml) concentrations of the lectin. The leukemic cells (LSL) also showed enhancement in EPM at low concentrations of Con A. At high concentrations of the same, however, the mean EPM of LSL was the same as that of untreated cells. In the case of NSL the reduction in EPM at high concentration of Con A is known to be brought about by post-redistributional binding of excess lectin to new receptor sites which emerge after capping of the first type of receptors. Similar investigations of the electrokinetic characteristics of Con A-receptor interaction on leukemic cells revealed that only a single type of receptor was present on LSL. These receptors were inducible to redistribution at low concentrations of Con A. High concentrations of the lectin, however, inhibited the redistribution of the receptors to Con A on LSL. This was confirmed when LSL treated with high concentrations of Con A were relieved from this inhibition by moderate concentrations of alpha-methyl glucoside, which dissociates cell bound Con A. Very low or very high concentrations of alpha-MG were ineffective. The receptors to Con A on LSL were thus behaviorally distinguishable from those on NSL. These data clearly demonstrate that the malignant transformation in AKR mice is also associated with alterations in the properties of receptors to a multivalent ligand Con A.