Control of Density and Microredistribution of Concanavalin-A Receptors in Rat Thymocytes at 4oC

Abstract

Previously it was reported that at 4.degree. C, a cooperative binding of concanavalin A [conA] to rat thymocytes occurred corresponding to a modification of the membrane leading to the recruitment of receptors and their immobilization. Apparently, both phenomena were modulated at 4.degree. C by drugs such as colchicine and cytochalasin B; cooperative binding of conA, which reflected receptor recruitment was only slightly modified by each drug alone. When the 2 drugs were used simultaneously, the binding of conA to rat thymocytes at low lectin concentrations was decreased, while at high concentrations it remained unchanged. Binding of succinyl-conA to drug-treated cells was lowered at all concentrations of lectin. The effects of colchicine and cytochalasin on the binding of horseradish perioxidase to cell-bound conA, or succinyl-conA were also studied. A decreased amount of horseradish peroxidase binding to conA bound to cells treated with colchicine to cytochalasin B occurred. In the presence of the 2 drugs, the decrease of peroxidase binding suggested a synergistic action of colchicine and cytochalasin B.