Y. Pacheco

Leukotriene B4 production by blood neutrophils in allergic rhinitis—effects of cetirizine

Background: Mucosal inflammatory processes in late phase of allergic diseases involve cytokine production, cell adhesion molecule overexpression and release of inflammatory mediators with chemotactic activity, such as leukolriene B4 (LTB4), We had previously observed increased production of LTB4 by neutrophils in patients with allergic rhinitis and discussed the role of granulocyte macrophage‐colony stimulating factor (GM‐CSF) priming. Some antihislaminic compounds were shown to diminish the production of leukotrienes by neutrophils.

Leukotriene B4 level in stimulated blood neutrophils and alveolar macrophages from healthy and asthmatic subjects. Effect of beta-2 agonist therapy.

Abstract. Leukotriene B4 levels were measured after stimulation by calcium ionophore A23187: (i) in peripheral neutrophils (PMN) from allergic asthmatics, rhinitis and healthy subjects; (ii) in macrophages collected by bronchoalveolar lavage. LTB4 levels in PMNs were significantly higher in non‐treated allergic asthmatics and non‐treated subjects with rhinitis compared to controls. Beta‐2 agonist‐treated asthmatics showed a significantly decreased LTB4 production which was not different from those of controls. In vitro, LTB4 production decreased significantly after PMN incubation with Salbutamol (10‐6 mo11‐1). LTB4 produced by AM collected by BAL was measured in non‐treated (n = 5) and treated (n= 11) asthmatics with inhaled beta‐2 agonist. AM collected from all controls and non‐treated asthmatics produced LTB4. By contrast, no production of LTB4 was observed in the treated group. LTB4 production decreased when normal AM were incubated in vitro with Salbutamol (10‐8 mol 1‐1). These results suggest that biochemical differences occur in PMN and macrophages from subjects treated with beta‐2 agonist, presumably in changing the 5‐lipoxygenase pathway.

Leukotriene B4 levels from stimulated neutrophils from healthy and allergic subjects: effect of platelets and exogenous arachidonic acid

Abstract. Leukotriene B4 (LTB4) levels were measured in peripheral blood neutrophils from allergic and healthy donors after stimulation by calcium ionophore A 23187. This level was higher in neutrophils from allergic subjects than in neutrophils from healthy subjects in the presence as well as in the absence of exogenous arachidonic acid. Platelets from allergics increased LTB4 levels from neutrophils from allergics but not levels in those from healthy donors. Moreover, platelets from healthy subjects reduced LTB4 in neutrophils from both groups. These results suggest that biochemical differences exist in neutrophils and platelets from allergics which contribute to changes in arachidonic acid metabolism via the 5‐lipoxygenase pathway. In addition, they support the concept that platelets may play an important role in the regulation of neutrophil LTB4 levels, possibly by affecting the 5‐lipoxygenase activity during the course of allergic inflammatory reactions.

Impaired G-proteins and cyclic nucleotide phosphodiesterase activity in T-lymphocytes from patients with sarcoidosis

Abstract. Among the various immune abnormalities which characterize active sarcoidosis, a low proliferative response of peripheral blood lymphocytes to mitogenic lectins has long been observed. Since membrane‐associated G‐proteins are very likely to be crucial elements in lectin signal transduction, we investigated the binding of 5′‐guanylylimidodiphosphate (GppNHp), a non hydrolyzable GTP analogue, to blood total lymphocyte membranes and to blood T‐lymphocyte membranes from patients with active sarcoidosis, and from healthy control subjects. GppNHp binding was markedly decreased in peripheral cells from patients with sarcoidosis as compared to controls, suggesting the occurence of a detect at the level of G‐protein(s). A further characterization of G‐proteins in these cells by means of ADP‐riboselabelling in the presence of bacterial toxins brought forward a significant decrease in the labelling of a 40 kDa protein, the major pertussis toxin substrate, in membranes from sarcoid patients, while the labelling of the major 44 kDa cholera toxin substrate proved to be unchanged with respect to control membranes. It is hypothesized that, in sarcoid lymphocytes, a detect in the negative control of adenylate cyclase mediated by the inhibitory G‐protein Gi, prevents the lowering of cAMP necessary to normal mitogenic response of blood lymphocytes to stimulation. cAMP degradation by the specialized enzyme phosphodiesterase constitutes another critical step in the control of cAMP levels. Both CAMP and cGMP phosphodiesterase activities were found decreased in blood total lymphocyte preparations from sarcoid patients. With purified T‐cells, although the mean cAMP and cGMP phosphodiesterase activities from sarcoid patients were found more markedly decreased with respect to healthy donors, only the decrease in cGMP phosphodiesterase was found statistically significant. The role these detects in cyclic nucleotide degradation potentially play in the disturbance of blood lymphocytes response associated with sarcoidosis is discussed

Cyclic nucleotide phosphodiesterases and methyltransferases in purified lymphocytes, monocytes and polymorphonuclear leucocytes from healthy donors and asthmatic patients

Abstract. Cyclic nucleotide phosphodiesterase and phospholipid N‐methyl‐transferase activities were simultaneously measured in purified polymorphonuclear cell‐, mononuclear cell‐, lymphocyte‐ and mono‐cyte‐homogenates from control subjects, from patients with atopic asthma and from patients with non‐atopic asthma. Whereas cyclic AMP and cyclic GMP phosphodiesterase activities were found to be about 10‐fold lower in polymorphonuclear than in mononuclear cells, phospholipid N‐methyltransferase proved to be rather similar in each cell type from control donors. Cyclic AMP phosphodiesterase and phospholipid N‐methyltransferase were significantly decreased in polymorphonuclear cells and monocytes from asthmatic patients compared with the control group while cyclic GMP phosphodiesterase was significantly impaired only in the monocyte subpopulation.

RU 41740 (BiostimR) stimulates the production of granulocyte macrophage colony-stimulating factor and interleukin-8 by human bronchial epithelial cells in vitro

1. 1. In this study, we observed the effects of RU 41740 (BiostimR) on the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-8 (IL-8) in human bronchial epithelial cells in vitro 2. 2. Cytokine production was assessed by enzyme-linked immunosorbent assay. 3. 3. We report that epithelial cells spontaneously released both cytokines and that RU 41740 induced a significant increase in production of IL-8 and GM-CSF. 4. 4. This is the first observation of a stimulatory effect of an immunostimulating compound used in humans on cytokine production by epithelial cells.