title: Platelet aggregating substance from mononuclear leukocytes.
abstract: Human peripheral blood mononuclear leukocytes (ML) in suspension stimulated with arachidonic acid (AA) were able to induce platelet aggregation. Shape change followed by first and second wave aggregation was the pattern of the platelet response. ML not treated with AA did not induce platelet aggregation nor did AA done at the concentration employed. The aggregating activity was not due to the ML presence, since cell-free supernatants of ML stimulated with AA induced similar platelet aggregation as the whole suspension. Aspirin incubated with ML-AA produced 65% reduction of the above aggregatory activity described while 38% and 45% reduction was obtained when ML-AA was incubated with 5, 8, 11, 14 eicosatetraynoic acid (ETYA) and nordihydroguaiaretic acid (NDGA). Complete platelet cyclooxygenase integrity was necessary to obtain the second wave of aggregation induced by ML-AA, while this was not required for the first wave response. We propose that ML-AA are able to produce a platelet activating substance(s) derived from AA metabolism involving cyclo and lipoxygenase actions. It is unlikely that this substance(s) is a hydroperoxyfatty acid or thromboxane A2 (TXA2) since it is active for at least two hours once generated.
mesh_terms: D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000328:Adult; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D001779:Blood Coagulation Factors / Q000502:physiology*; D002396:Catechols / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009637:Masoprocol; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D010972:Platelet Activating Factor; D010974:Platelet Aggregation / Q000187:drug effects
chemical_list: D001095:Arachidonic Acids; D001779:Blood Coagulation Factors; D002396:Catechols; D010972:Platelet Activating Factor; D015117:5,8,11,14-Eicosatetraynoic Acid; D016718:Arachidonic Acid; D009637:Masoprocol; D001241:Aspirin