G protein activation and mediator release from human neutrophils and platelets after stimulation with sodium fluoride and receptor-mediated stimuli.
Human polymorphonuclear granulocytes (PMN) and platelets were pre-activated with a receptor-mediated stimulus [formyl-methionyl-leucyl-phenylalanine (FMLP) or thrombin, respectively] and subsequently incubated with sodium fluoride (NaF). We investigated various cell responses, such as chemiluminescence by PMN, platelet aggregation and the release of lipid mediators [i.e. leukotriene B4 (LTB4) and its omega-oxidation products from neutrophils and 12-hydroxy-eicosatetraenoic acid (12-HETE) from platelets]. As a marker of G protein involvement, the binding of [3H]guanylylimidodiphosphate (Gpp (NH) p) to the membrane fractions of stimulated cells was determined. PMN pre-stimulated with FMLP showed a synergistically enhanced generation of leukotrienes returning to control values with the time of preincubation. Platelets preliminary treated with thrombin followed by incubation with NaF resulted in a sub-additive and time-independent mediator generation. Neither chemiluminescence by PMN nor platelet aggregation showed a similar pattern compared to the mediator release: PMN preincubated with FMLP followed by NaF resulted in a second chemiluminescence response; the aggregation of platelets which were preincubated with thrombin was partially inhibited by the addition of NaF. Membrane fractions isolated from FMLP-pre-stimulated neutrophils showed a pattern in [3H]Gpp (NH) p-binding capacity that was comparable to the respective leukotriene release. With thrombin-prestimulated platelets, no similarities between Gpp (NH) p binding, aggregation or 12-HETE generation were observed. The sequential activation of different cell populations using the same kind of stimulation lead to different cell responses, indicating the diversity of G proteins and their control mechanisms.
Brom
C
C
Lehrstuhl für Medizinische Mikrobiologie und Immunologie, Ruhr-Universität Bochum, Germany.
Brom
J
J
König
W
W
D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D019204:GTP-Binding Proteins / Q000097:blood*; D006801:Humans; D007975:Leukotriene B4 / Q000097:blood; D008163:Luminescent Measurements; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology*
D010975:Platelet Aggregation Inhibitors; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D012969:Sodium Fluoride; D019204:GTP-Binding Proteins