Activation of phospholipase D in a rat mast (RBL 2H3) cell line. A possible unifying mechanism for IgE-dependent degranulation and arachidonic acid metabolite release.
RBL 2H3 cells (a model of mast cell function) were sensitized with anti-TNP IgE (0.5 micrograms/ml) and triggered to secrete both histamine and arachidonic acid (AA) metabolites by the addition of TNP-OVA (0 to 100 ng/ml). After a 3-min delay, the release of both groups of mediators proceeded in a parallel manner. In cells labeled with [14C]-AA, TNP-OVA produced a rapid increase in phosphatidic acid (PA), and subsequently, 1,2-diacylglycerol (DAG) and intracellular AA levels. Concurrently, there was a decrease in [14C]-AA labeled phosphatidylcholine. The release of labeled AA from phosphatidylcholine in response to TNP-OVA was paralleled by a liberation of free choline but no evidence of liberation of phosphorylcholine. When ethanol (0.05 to 2% v/v) was included in the culture medium, phosphatidylethanol was synthesized at the expense of PA and DAG, with a resulting inhibition of secretion. D,1 propranolol, an inhibitor of PA phosphohydrolase, inhibited the IgE-dependent production of [14C]-DAG, and [14C]-free fatty acid but not [14C]-PA. The IgE-dependent release of both histamine and AA metabolites was completely inhibited by pretreatment with propranolol. Taken together, the above results suggest that phospholipase D is activated upon cross-bridging of IgE receptors on the surface of RBL 2H3 cells and that this may be a pivotal step in the signal transduction cascade leading to the release of both presynthesized and de novo synthesized mediators.
Lin
P Y
PY
Department of Pharmacology, Hoffmann-La Roche, Nutley, NJ 07110.
Wiggan
G A
GA
Gilfillan
A M
AM
D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000502:physiology; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D015550:Cell Degranulation / Q000276:immunology*; D004789:Enzyme Activation; D006636:Histamine Release / Q000276:immunology; D007073:Immunoglobulin E / Q000502:physiology*; D015289:Leukotrienes / Q000378:metabolism; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology*; D010047:Ovalbumin / Q000276:immunology; D010739:Phospholipase D / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011961:Receptors, Fc / Q000502:physiology; D017455:Receptors, IgE; D015398:Signal Transduction / Q000276:immunology; D014407:Tumor Cells, Cultured
D000944:Antigens, Differentiation, B-Lymphocyte; D001095:Arachidonic Acids; D015289:Leukotrienes; D011961:Receptors, Fc; D017455:Receptors, IgE; C038600:trinitrophenyl-ovalbumin; D016718:Arachidonic Acid; D007073:Immunoglobulin E; D010047:Ovalbumin; D011433:Propranolol; D010739:Phospholipase D