Inhibition of sphingolipid synthesis impairs cellular activation, cytokine production and proliferation in human lymphocytes.
The localisation of the T cell receptor and other signalling molecules in membrane microdomains (MM) is essential for the activation of T lymphocytes. These MM are stabilized by sphingolipids and cholesterol. It was recently shown that the activation of T lymphocytes leads to the confluence of small MM and the formation of an immunological synapse which is thought to be essential for a persistent activation and proliferation. We studied the effects of an inhibition of sphingolipid synthesis on T lymphocyte function. Both sphingolipid inhibitors, PDMP and myriocin, inhibited glucosphingolipids in whole cell lipid extracts and in MM. Both compounds inhibited the proliferation of superantigen-stimulated PBMC without inducing cell death. However, only the ceramide-like compound PDMP inhibited the expression of activation markers and the secretion of IFN-gamma which was not seen with myriocin treatment. The MM localisation of Lck and LAT was not significantly reduced in PDMP-treated cells. In conclusion, our results show that glucosphingolipids are necessary for cell growth of human T lymphocytes. However, inhibition of glucosphingolipid synthesis itself did not inhibit cellular activation. Our data show that glucosphingolipids - in contrast to cholesterol - are not essential for the stabilisation of MM.
Blank
Norbert
N
Department of Internal Medicine V, Division of Rheumatology, University of Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany. Norbert_Blank@med.uni-heidelberg.de
Schiller
Martin
M
Gabler
Christoph
C
Kalden
Joachim R
JR
Lorenz
Hanns-Martin
HM
D002455:Cell Division / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D002855:Chromatography, Thin Layer; D016207:Cytokines / Q000096:biosynthesis*; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D021962:Membrane Microdomains; D009025:Morpholines / Q000494:pharmacology; D013107:Sphingolipids / Q000096:biosynthesis*
D016207:Cytokines; D009025:Morpholines; D013107:Sphingolipids; C033110:RV 538