title: Comparative platelet inhibitory effects of human neutrophils and lymphocytes.
abstract: The effects of isolated leukocytes (polymorphonuclear leukocytes [PMNLs] or neutrophils and lymphocytes) on platelet aggregation in platelet-rich plasma (PRP) were examined. Both PMNLs and lymphocytes decreased platelet aggregation in a concentration-dependent fashion. PMNL-induced, but not lymphocyte-induced, inhibition of platelet aggregation was more pronounced as the incubation time of PRP with PMNLs was prolonged. The platelet-inhibitory effect of PMNLs was enhanced by superoxide dismutase (SOD) and was attenuated by oxyhemoglobin and methylene blue. These agents, in contrast, had no effect on lymphocyte-mediated inhibition of platelet aggregation. Adenosine deaminase did not modulate the platelet inhibitory effects of either PMNLs or lymphocytes. The incubation of PMNLs with PRP was associated with an increase in cyclic guanine 5' monophosphate (cGMP) levels in PRP. Incubation of lymphocytes, however, did not result in an increase in cGMP levels in PRP. Neither PMNLs nor lymphocytes in PRP caused a reduction in thromboxane B2 (TXB2) or an increase in 6-keto-PGF1 alpha. Thus this study shows potent inhibitory effects of isolated PMNLs mediated by a substance with biologic characteristics of nitric oxide. However, the mechanism of lymphocyte-induced inhibition of platelets appears to be independent of prostaglandins, nitric oxide, or adenosine.
authors.affiliation: Department of Medicine, University of Florida College of Medicine, Gainesville.
authors.forename: F A
authors.initials: FA
authors.lastname: Nicolini
authors.forename: A C
authors.initials: AC
authors.lastname: Wilson
authors.forename: P
authors.initials: P
authors.lastname: Mehta
authors.forename: J L
authors.initials: JL
authors.lastname: Mehta
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D001798:Blood Proteins / Q000378:metabolism / Q000502:physiology*; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D006152:Cyclic GMP / Q000097:blood; D006801:Humans; D007962:Leukocytes / Q000378:metabolism / Q000502:physiology; D008214:Lymphocytes / Q000378:metabolism / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism / Q000502:physiology*; D013929:Thromboxane B2 / Q000097:blood
chemical_list: D001798:Blood Proteins; C052788:platelet inhibitory factor; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D006152:Cyclic GMP