Inhibition of interleukin-2-stimulated enhancement of human natural killer (NK) cell activity by carbaryl, an anticholinesterase insecticide.

The potency of the anticholinesterase (antiCHE) insecticides as serine hydrolase inhibitors, and evidence for serine hydrolase activity in interleukin-2 (IL2) signalling suggest that the natural killer (NK) cell may be a target for dysregulation by antiCHE insecticides. NK cells are large granular lymphocytes (LGL) that respond to IL2 by proliferating and increasing their cytolytic efficiency. In the present study, we assessed the effects of carbaryl (CA, an antiCHE insecticide) and alpha-naphthol (NA, the major metabolite of CA) on both target cell killing per se and IL2 enhancement of target cell killing by human NK cells. Human LGL, collected from the peripheral blood of normal donors, were cultured for 4 days with human recombinant IL2 (HRIL2), then assayed by a 51Chromium (51Cr) release assay for lytic activity against human K562 cells. When added at the beginning of the culture period, CA inhibited enhancement of cytolytic efficiency in a concentration-dependent manner; at concentrations (0.5 and 5.0 microM) compatible with no cholinergic toxicity. Reduction of the effector/target cell (E/T) ratio in the 51Cr release assay markedly enhanced the observed inhibition by CA. In one experiment, inhibition increased from 6% to 20%, 17% to 35%, and 53% to 73% at 0.5, 5.0, and 50 microM CA, respectively, when E/T was reduced from 10:1 to 2.5:1. This result is consistent with reduced cytolytic efficiency of individual NK cells exposed to CA. NA had no effect at 0.5 or 5.0 microM but caused some inhibition at 50 microM. Neither CA nor NA produced LGL death. When CA or NA was added directly to the 51Cr release assay, inhibition was not observed. The mechanism of inhibition of IL2-stimulated enhancement of target cell killing is not yet known, however, the results are consistent with impairment of IL2 signalling, by CA.     

Percutaneous balloon valvotomy for the treatment of isolated tricuspid stenosis

A 46-year-old woman with isolated tricuspid stenosis complained of increasing fatigue and dyspnea on exertion. Exercise Doppler echocardiography reproduced her symptoms and revealed a marked increase in trans-tricuspid gradient. Successful percutaneous balloon tricuspid valvotomy was performed, with resolution of her symptoms.     

Characterization of histamine H-1 receptors on human mononuclear cells

Histamine H-1 receptors on peripheral human mononuclear cells were characterized by radioligand binding of the H-1 receptor antagonist [3H]pyrilamine to lymphocyte-rich preparations. Simultaneous computerized analyses of sixteen separate equilibrium-binding assays indicated the presence of two distinct classes of binding sites with dissociation constants (Kds) of 4 +/- 1 nM and 55 +/- 9 microM and binding capacities of 21 +/- 7 fmol and 117 +/- 15 pmol/million cells, respectively. Competition binding curves for displacement of [3H]pyrilamine binding by histamine receptor agonists and antagonists also indicated the presence of multiple binding sites for the H-1 receptor. Further, the ED50 values determined for histamine receptor agonists and antagonists were entirely consistent with the expected rank order of potency for interactions with H-1 receptors. Thus, human mononuclear cells have a large number of H-1 receptors that exhibit two distinct binding sites, and the Kds for these sites are within the range of histamine concentrations achieved either in physiologic states or after mast cell (or basophil) degranulation.     

Eosinophil migration in response to three molecular species of platelet activating factor

Multiple molecular species of the eosinophil chemoattractant platelet activating factor (PAF) are produced as a result of inflammatory processes. We therefore compared the ability of three naturally occurring PAF species (C160, C180, and C181), which only varied at carbon 1, to induce eosinophil chemotaxis through naked 3-m pore polycarbonate filters. Timecourse experiments indicated that all species of PAF tested induced significant and equivalent eosinophil migration at 1 h which peaked at 2 h. Overall, the rank order of chemotactic potency for the PAF species was relatively equivalent. The specific PAF antagonist WEB 2086 inhibited eosinophil migration induced by all three PAF species equally. We conclude that the degree of PAF-induced eosinophil migration is not dependent upon the molecular species of PAF.accepted by G. W. CarterThis work was supported in part by a Veterans Administration Merit Review Award.     

Cytokines induce selective granulocyte chemotactic responses

Neutrophils, eosinophils and cytokines are important in allergic airway inflammatory responses. However, it is unclear how cytokines selectively influence neutrophils versus eosinophils to migrate to an inflammatory site. The cytokines, transforming growth factor-1 (TGF-1), interleukin (IL)-1, IL-5, IL-8, granulocyte macrophage-colony stimulating factor (GM-CSF) and tumor necrosis factor- (TNF-), are released subsequent to allergic reactions and affect both neutrophil and eosinophil functions. We studied whether these cytokines differed in capacity to induce human neutrophil versus eosinophil migration through naked filters and human umbilical vein endothelial cell (HUVEC) and human pulmonary type II-like epithelial (A549) cell monolayers grown on filters. Dose-response experiments using all barriers were performed for each granulocyte and cytokine. TGF-1 did not induce granulocyte migration. IL-5 induced eosinophil migration only through naked filters. IL-1 stimulated neutrophil migration through cellular barriers, but not through naked filters. TNF- and GMCSF induced neutrophil and eosinophil migration through filters, but only neutrophil migration through cellular monolayers. Only IL-8 induced significant neutrophil and eosinophil migration; however, there were clear-cut differences between the neutrophilotactic and eosinophilotactic responses through all barriers emploved. Thus, our data show that these cytokines induce distinct chemotactic responses for neutrophils versus eosinophils. Moreover, by using relevant cellular barriers versus naked filters, our data better examines the capability of these cytokines to induce selective granulocyte migration to an inflammatory site in lung diseases such as asthma.accepted by G. W. Carter