Free cytoplasmic calcium concentration and the mitogenic stimulation of lymphocytes.
The effects of the lectins concanavalin A, succinylated concanavalin A, and wheat germ agglutinin on the free cytoplasmic Ca2+ concentration in mouse thymocytes were measured using the fluorescent Ca2+ indicator "quin 2" (Tsien, R. Y. (1980) Biochemistry 19, 2396-2404) and compared with the metabolic and mitogenic effects of the lectins on the cells. Within 1 min of adding each ligand, there is a dose-dependent increase in the free cytoplasmic Ca2+ concentration reported by quin 2. This response is selective for Ca2+, but it does not coincide closely with the subsequent mitogenic stimulation at 48 h by concanavalin A or succinyl concanavalin A. The nonmitogenic lectin wheat germ agglutinin also causes an increase in free cytoplasmic Ca2+ concentration and early metabolic stimulation of the cells, but stimulation is self-aborted before DNA synthesis occurs. At the intracellular concentrations of quin 2 required for measurement of the free Ca2+ concentration, the chelator causes early metabolic stimulation of the cells very similar to that produced by concanavalin A and the mitogenic Ca2+ ionophore A23187. Thus, phosphatidylinositol metabolism and lactate production are stimulated in mouse thymocytes and pig lymphocytes within 1 h of loading with quin 2 and significant increases in RNA synthesis occur after 8 h. Quin 2 causes mitogenic stimulation of pig lymphocytes measured as increased [3H]thymidine uptake at 48 h, that is variable but substantial in most experiments (up to 100% of the stimulation by A23187). The chelator itself has no significant activity as a Ca2+ ionophore, but the apparent free Ca2+ concentration in the cells increases both with the concentration of intracellular quin 2 and with the extracellular Ca2+ concentration. These data leave open the possibility that quin 2 itself affects the concentration of free Ca2+ or other cations in the cells.
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003208:Concanavalin A / Q000031:analogs & derivatives / Q000494:pharmacology; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D037102:Lectins / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D010716:Phosphatidylinositols / Q000378:metabolism; D013552:Swine; D013601:T-Lymphocytes / Q000187:drug effects*; D013936:Thymidine / Q000378:metabolism; D014529:Uridine / Q000378:metabolism; D014909:Wheat Germ Agglutinins
D000634:Aminoquinolines; D007773:Lactates; D037102:Lectins; D010716:Phosphatidylinositols; D014909:Wheat Germ Agglutinins; D003208:Concanavalin A; D019344:Lactic Acid; C019558:succinylconcanavalin A; C035739:Quin2; D002118:Calcium; D013936:Thymidine; D014529:Uridine