Fisons plc was a British multinational pharmaceutical, scientific instruments and horticultural chemicals company headquartered in Ipswich, United Kingdom. It was listed on the London Stock Exchange and was once a constituent of the FTSE 100 Index. It was acquired by Rhone-Poulenc in 1995.
SummaryBackground Comparable T cell‐containing and T cell‐depleted culture systems for human IgE synthesis are currently not available.Objective This has prompted us to develop peripheral blood mononuclear cell (PBMC) based culture systems for human IgE synthesis in the presence and absence of T cells.Methods In this paper we describe simplified conditions for in vitro synthesis of high levels of IgE by human peripheral blood B cells, both in T cell‐containing cultures and in anti‐CD40 stimulated T cell‐depleted cultures.Results T cell‐depieted cultures released approximately 20 times more IgE [range 410–2220 ng/mL (mean 1270 ng/mL); based on six experiments using cells from three donors] than did T cell‐containing cultures [range 23–105 ng/mL (mean 58 ng/mL); based on 15 experiments using cells from three donors]. Reconstitution experiments were performed to investigate the role of T eells on IgE synthesis. Adding T eells back to the anti‐CD40 stimulated T cell‐depleted cultures resulted in a dose‐dependent inhibition of IgE production. In the absence of anti‐CIMO low numbers of T cells stimulated, while high numbers suppressed, IgE production: the optimal ratio of T cells to non‐T cells for maximal IgE production was found to be 1:1. At this ratio, irradiated (non‐replicating) T cells supported a much greater IgE synthesis than did non‐irradiated T cells.Conclusion The development of these systems provides directly comparable T cell‐containing and T cell‐depleted cultures for human IgE synthesis from peripheral blood, allowing further study of the role of T cells in IgE regulation. These systems will also be of use for determining whether potential modulators of IgE synthesis act on the T cells or on other cell types.
1 We have studied the effects of the reported chloride channel blocker, sodium cromoglycate, on volume-activated Cl- currents in endothelial cells from bovine pulmonary artery by means of the whole-cell patch clamp technique. Cl- currents were activated by challenging the cells with a hypotonic extracellular solution of 60% of the normal osmolarity.2 Half maximal activation of the current at + 95 mV occurred after exposure of the cells for 148 +/- 10 s (n = 6) to hypotonic solution (HTS). At the same membrane potential but in the presence of 100 mu M sodium cromoglycate (disodium-1,3-bis (2'-carboxylate-chromone-5'-yloxy)-2-hydroxy-propane) activation was delayed (253 +/- 25 s, n = 6) and the maximal current amplitude was reduced to 63 +/- 7% of the control (n = 13).3 In comparison, an equimolar concentration of NPPB (5-nitro-2(3-phenyl) propylamino-benzoic acid), another Cl- channel blocker, completely blocked the volume-activated current in less than 20 s.4 Sodium cromoglycate, applied at the time when the HTS-induced current was completely activated, dose-dependently inhibited this current with a concentration for half maximal inhibition of 310 +/- 70 mu M. Data for nedocromil sodium were not significantly different from those for sodium cromoglycate.5 Sodium cromoglycate, loaded into the endothelial cells via the patch pipette in ruptured patches, resulted in a decline of the HTS activated current with a time course that was compatible with diffusion of the compound from the pipette into the cell. Intracellulary applied sodium cromoglycate was also more effective and at 50 mu M caused a decrease in the amplitude of the current to 25 +/- 6% (n = 10) of the control current.6 It is concluded that blockade of volume-activated Cl- currents by extracellular sodium cromoglycate may be due to an intracellular action following its permeation across the cell membrane.
Angular intensity distribution of molecular ions ejected in matrix-assisted laser desorption/ionization (MALDI) have been measured for two symmetrical positions of the laser beam with respect to the sample surface normal (+60 degrees and -60 degrees). It is shown that the molecular ions are ejected in the direction opposite to the incident laser beam with an average angle of similar to 30 degrees which does not depend on the molecular weight in the mass range m/z = 1000 to 25 000. Experiments were performed with the matrix alpha-cyano4-hydroxy-cinnamic acid.
Abstract: Retinoic acid‐treated murine P19 embryonal carcinoma cells differentiate into cells with neuronal morphology that display typical neuronal markers. In this study, the presence of glutamate receptors linked to Ca2+‐signaling mechanisms on these neurons was demonstrated by testing the effects of glutamate agonists and antagonists on the intracellular calcium ion concentration ([Ca2+]i). Glutamate (1 mM) induced either sustained or transient increases in [Ca2+]i. The sustained glutamate‐induced increase in [Ca2+]i was mimicked by NMDA (40 µM). The NMDA‐triggered [Ca2+]i response was abolished by incubating the cells in Ca2+‐free medium or by pretreating them with Mg2+ (2 mM) or MK‐801 (0.1 µM). These responses were unaffected by the non‐NMDA antagonist CNQX (10 µM), but they required glycine (3–30 µM). Kainate (40 µM) and AMPA (40 µM) did not affect [Ca2+]i. Without external Ca2+, glutamate triggered transient, sometimes oscillating, increases in [Ca2+]i. These responses were mimicked by the metabotropic agonist trans‐(1S,3R)‐1‐amino‐1,3‐cyclopentanedicarboxylic acid (300 µM). These results suggest that neurons derived from P19 embryonal carcinoma cells have NMDA and metabotropic, but not AMPA/kainate receptors, which are linked to Ca2+‐signaling mechanisms. These cells could provide a consistent and reproducible model with which to study neuronal differentiation, neurotoxicity, and glutamate receptor‐signaling mechanisms.
