Arachidonic Acid Metabolism in Guinea Pig Eosinophils: Synthesis of Thromboxane B2 and Leukotriene B4 in Response to Soluble or Particulate Activators

Abstract

The arachidonic acid metabolism of guinea pig eosinophils isolated from either peritoneal cavity or bronchoalveolar lavages was studied by reverse-phase high-performance liquid chromatography. The purified eosinophils (95-100%) from either source released thromboxane B2 (TxB2), luekotriene B4 (LTB4) and 5-hydroxy eicosatetraenoic acid (5-HETE) following calcium ionophore A23187 stimulation. Quantification by radioimmunoassay indicated that maximal mediator output from the stimulated peritoneal cells was reached at 3 min after stimulation. The increase in production of TxB2 and LTB4 was correlated to increasing calcium ionophore A23187 concentration up to 1.0 micrograms/ml. In addition to calcium ionophore, the guinea pig peritoneal cells were also activated by f-met-leu-phe, phorbol 12-myristate, 13-acetate (PMA), and to lesser extent platelet-activating factor (PAF) to produce TxB2. LTB4 synthesis was stimulated by calcium ionophore, by f-met-leu-phe, as well as by unopsonized glucan, a particulate phagocytotic stimulus. The guinea pig eosinophils do not synthesize sulfidopeptide leukotrienes because of the absence of the specific LTA4 glutathione S-transferase. These results suggest that the guinea pig eosinophils differ from the human circulating eosinophils in the synthetic capacity of lipid mediators derived from arachidonic acid metabolism. This difference may be important in the understanding of the role of the eosinophils in inflammatory reactions such as that which occurs in the bronchial tissues of asthmatics.