Wheat germ agglutinin activates human T lymphocytes by stimulation of phosphoinositide hydrolysis.
Recently, it has become evident that stimulated phosphoinositide (PI) hydrolysis plays a crucial role in early T lymphocyte activation. We have investigated the effects of the nonmitogenic lectin wheat germ agglutinin (WGA) on several parameters associated with PI hydrolysis in human T cells. It was found that WGA was as effective as anti-T3 antibody and PHA in producing a rise in cytosolic free Ca++ ((Ca++)i) in blood T cells and in cells of the T cell line CCRF-CEM. It was inferred that identical cells within the blood T cell preparation responded to each of the three agents, refuting the contention that WGA only stimulated a subfraction of circulating mature T lymphocytes. WGA-induced, but not PHA-induced rises in (Ca++)i could be blocked completely by N-acetyl-D-glucosamine, demonstrating that the sugar-binding characteristics of the lectin dictate its action on T lymphocytes. Anti-T3 antibody, PHA, and WGA all initiated inositol phosphate formation in blood T cells, indicating that each of the agents stimulated PI hydrolysis. The combination of WGA with nonmitogenic amounts of phorbol-12-myristate-13-acetate resulted in strong mitogenicity. It is concluded that WGA, like anti-T3 antibody and PHA, is a pan-T activator of PI hydrolysis.
D000634:Aminoquinolines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D037102:Lectins / Q000494:pharmacology*; D008213:Lymphocyte Activation; D010716:Phosphatidylinositols / Q000096:biosynthesis / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014909:Wheat Germ Agglutinins
D000634:Aminoquinolines; D037102:Lectins; D010716:Phosphatidylinositols; D014909:Wheat Germ Agglutinins; C035738:Quin2-acetoxymethyl ester; D002118:Calcium