Platelet aggregation inhibition by mononuclear leukocytes.
In this study we have investigated the effect of human mononuclear leukocytes (ML) on platelet aggregation. The results obtained demonstrated that coincubation of platelets with nonstimulated ML decreased platelet aggregation induced by collagen or thrombin in a concentration-dependent manner. The inhibitory effect increased with the incubation period of the cells, reaching a plateau at 5 minutes. T and non-T enriched ML suspensions exerted an inhibitory effect similar to the total population of ML. Supernatants from ML or mixed cell suspensions also diminished platelet aggregation. 6-keto PGF1 alpha concentration in the supernatants was less than 10 pg/ml. Hemoglobin, L-arginine and cytochrome C did not modify the antiaggregating activity of ML, whereas superoxide dismutase potentiated the inhibition of aggregation mediated by ML. The inhibitory effect was not modified by monoclonal antibody (MoAb) against the lymphocyte function-associated antigen 1, alpha subunit (LFA-1 alpha) or by a MoAb directed against P-selectin. Our results demonstrated that ML inhibited platelet aggregation, at least partially, by the release of a soluble factor(s) distinct of prostacyclin or nitric oxide. Surface adhesion molecules seem also not to be involved.
Schattner
M A
MA
Departamentos de Hemostasia y Trombosis e Inmunología Academia Nacional de Medicina, Buenos Aires, Argentina.
Finiasz
M R
MR
Notrica
J A
JA
Lazzari
M A
MA
D015121:6-Ketoprostaglandin F1 alpha / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001120:Arginine / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D003574:Cytochrome c Group / Q000494:pharmacology; D005340:Fibrinogen / Q000494:pharmacology; D006454:Hemoglobins / Q000494:pharmacology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000502:physiology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000276:immunology; D016131:Lymphocyte Subsets / Q000502:physiology; D009000:Monocytes / Q000502:physiology; D019007:P-Selectin; D010974:Platelet Aggregation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology; D013482:Superoxide Dismutase / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D017077:Culture Media, Conditioned; D003574:Cytochrome c Group; D006454:Hemoglobins; D016169:Lymphocyte Function-Associated Antigen-1; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins; D015121:6-Ketoprostaglandin F1 alpha; D005340:Fibrinogen; D003094:Collagen; D001120:Arginine; D013482:Superoxide Dismutase; D013917:Thrombin