Diacylglycerol and ceramide kinetics in primary cultures of activated T-lymphocytes.
T cell activation results in the generation of diacylglycerol (DAG), the physiological activator of protein kinase C. Recently, ceramide, a bioactive lipid intracellular second messenger, has been shown to play a positive role in T cell proliferation. Most studies examining mitogen induction of DAG and ceramide in T cells have been conducted in cell lines over short periods of time (0-30 min) relative to the 2-3-h time frame required for commitment to proliferation. Therefore, we examined T cell mitogen-induced DAG and ceramide kinetics under physiologically relevant conditions during the initial 2 h of culture. Freshly isolated murine splenic lymphocytes were stimulated with the T cell-specific mitogen, concanavalin A (Con A). Our results show that Con A induced a multiphasic DAG response with significant peaks in DAG mass occurring at 2, 20 and 120 min. Concomitantly, ceramide mass was significantly increased 2 min following Con A addition and remained elevated until 120 min. Addition of C8-ceramide (10 microM) to lymphocyte cultures significantly enhanced mitogen-induced proliferation. These results demonstrate that DAG is continuously produced by activated T lymphocytes in a multiphasic fashion, and that ceramide is a positive effector molecule with respect to murine T cell proliferation. These results establish a foundation for further examination of the relationship between DAG, ceramide and T cell activation.
Jolly
C A
CA
Faculty of Nutrition, Texas A and M University, College Station 77843, USA.
Laurenz
J C
JC
McMurray
D N
DN
Chapkin
R S
RS
D000818:Animals; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism* / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology*; D004075:Diglycerides / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D015398:Signal Transduction / Q000187:drug effects; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*
D002518:Ceramides; D004075:Diglycerides; D003208:Concanavalin A