calcimycin and 8-phenyltheophylline

The purpose of this study was to investigate a possible relationship between human umbilical vein endothelial cells (EC) triggered by ionophore A23187 at different doses (0.5-2.5 microM) and polymorphonuclear neutrophils (PMN). EC supernatants were shown to contain neutrophil chemoattractant activity (NCA) and in parallel a factor inducing an inhibition of PMN chemiluminescence (PMN CL). Supernatants obtained from EC triggered by A23187 exhibited a high level of NCA (73 +/- 5 PMN.hpf-1 compared to 21 +/- 4 PMN.hpf-1 in untreated EC supernatants, p less than 0.01). This NCA was independent from arachidonic acid metabolites, since indomethacin and nordi-hydroguaiaretic acid failed to suppress the chemotactic activity. Using gel filtration chromatography (AcA 54) the NCA was recovered in a single peak of apparent molecular weight of 37,000 +/- 4,000 daltons. Checkerboard analysis indicated that NCA exhibited both chemotactic and chemokinetic activities. In addition, supernatants of A23187-stimulated EC, and at a lesser degree, supernatants of unstimulated EC, inhibited PMN CL induced by N-formyl-Methionyl-Leucyl-Phenylalanine (61% inhibition, p less than 0.05), and by A23187 itself (80% inhibition, p less than 0.01), but not that induced by phorbol-myristate-acetate. Indomethacin and protamine sulphate did not modulate this inhibitory activity. By contrast, EC-derived inhibitory activity was inhibited (50%) by an adenosine antagonist (8-phenyltheophylline), indicating a participation of adenosine in this inhibitory activity of PMN CL. These data suggest the possibility that activated endothelial cells could both enhance PMN migration and protect themselves against potential damaging effects of oxygen metabolites produced by PMN, particularly during transvascular migration.

Topics: Calcimycin; Cell Communication; Chemotaxis, Leukocyte; Endothelium, Vascular; Fetal Blood; Humans; In Vitro Techniques; Indomethacin; Luminescent Measurements; Masoprocol; Models, Biological; Neutrophils; Theophylline; Umbilical Veins

5'-N-ethylcarboxamideadenosine (NECA) greater than 2-chloroadenosine greater than adenosine greater than (-)-N6-(R-phenyl-isopropyl)-adenosine greater than (+)-N6-(S-phenylisopropyl)-adenosine, in that order of potency, inhibited in vitro antigen-induced histamine release from human basophils in a dose-dependent fashion. Inhibition occurred only during the first stage of antigen-induced histamine release and the nucleosides failed to inhibit the release caused by the Ca2+ ionophore, A23187. 6-nitrobenzylthioinosine and dipyridamole, which inhibit adenosine uptake, and erythro-9-(2-hydroxy-3-nonyl)adenine, which blocks adenosine metabolism, did not impair the inhibition caused by NECA and adenosine. 8-phenyltheophylline and theophylline, two competitive antagonists of adenosine receptors, blocked the inhibition caused by NECA and adenosine. These data suggest that NECA and other adenosine analogs activate a specific cell surface adenosine receptor which possesses properties similar to those of an adenosine A2/Ra receptor.

Topics: Adenosine; Adenosine-5'-(N-ethylcarboxamide); Adenylyl Cyclases; Basophils; Biological Transport; Calcimycin; Histamine Release; Humans; Receptors, Cell Surface; Receptors, Purinergic; Structure-Activity Relationship; Theophylline; Thioinosine