title: Platelet-activating factor (PAF-acether) induced leukotriene C4 formation and luminol dependent chemiluminescence by human eosinophils.
abstract: Human eosinophils are capable of synthesizing almost exclusively the strongly spasmogenic compound LTC4 when stimulated with either the calcium ionophore A 23187 or opsonized zymosan (OZ). Although PAF-acether in concentrations ranging from 10 nM to 1 microM is hardly capable of inducing significant LTC4 synthesis itself, it significantly enhances the OZ-induced LTC4 formation at a concentration of 1 microM. However, at a concentration of 10 microM, PAF-acether itself is capable of inducing LTC4 formation comparable with that induced by OZ. PAF-acether, at a concentration of 10 microM (and not at a concentration of 1 microM) is also capable of inducing a luminol dependent chemiluminescent response by eosinophils. The PAF-acether antagonist BN 52021 at a concentration of 0.1 mM not only partially inhibited the PAF-acether induced LTC4 formation but also the OZ induced LTC4 formation. Since an equal inhibition is found the inhibitory mode of action of BN 52021 is most likely directed towards a common pathway. Taken together, these results suggest that eosinophils may be triggered by high locally reached concentrations of PAF-acether to release inflammatory and bronchoconstrictive mediators. This may be of importance for the pathogenesis of the allergen induced late phase asthmatic reaction.
mesh_terms: D004804:Eosinophils / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008165:Luminol / Q000502:physiology*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000502:physiology*; D011724:Pyridazines / Q000502:physiology*; D013189:SRS-A / Q000096:biosynthesis*; D015054:Zymosan / Q000494:pharmacology
chemical_list: D010972:Platelet Activating Factor; D011724:Pyridazines; D013189:SRS-A; D009240:N-Formylmethionine Leucyl-Phenylalanine; D008165:Luminol; D015054:Zymosan