Comparison of the action of calcium antagonists on basophil histamine release

Human basophil histamine release is differently affected by inhibitors of calmodulin, diacylglycerol kinase and peptidyl prolyl cis-trans isomerase in a secretagogue specific manner

To assess the role of calmodulin in human basophil histamine release, we triggered leukocytes with different secretagogues in the presence of putative inhibitors of calmodulin. Calcium ionophore-induced histamine release was reduced or blocked by calmidazolium, CGS 9343B, felodipine, metofenazate, and Ro 22-4839. H 186/86, a felodipine-related dihydropyridine derivative, blocked A23187-but not ionomycin-triggered histamine release, suggesting a difference in the mode of action of these ionophores. In contrast, leukocyte histamine release triggered by the purported protein kinase C (PKC) activator, 1,2-isopropylidene-3-decanoyl-sn-glycerol (IpOCOC9), was enhanced by calmidazolium, CGS 9349B and metofenazate but not affected by felodipine or Ro 22-4839, whereas the response triggered by 4 beta-phorbol 12-myristate 13-acetate (PMA) was reduced by metofenazate and Ro 22-4839 but not consistently affected by calmidazolium, CGS 9343B or felodipine. The PMA-induced histamine release was enhanced by H 186/86. Anti-IgE- and FMLP-induced responses were either unaffected or slightly enhanced by the examined calmodulin antagonists. In comparison with the calmodulin antagonists, R 59022, an inhibitor of diacylglycerol kinase, failed to reduce calcium ionophore-triggered histamine release, whereas FK506, an inhibitor of peptidyl prolyl cis-trans isomerase (PPI), reduced both anti-IgE- and ionophore-triggered responses. These results indicate that calmodulin constitutes an obligate link in signal transduction pathways leading to human leukocyte histamine release if the trigger is a calcium ionophore but not when responses are induced by anti-IgE, FMLP or PMA; a calmodulin-dependent component may rather balance responses induced by IpOCOC9.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition by galanin and by high K+ of human basophil histamine release triggered by calcium ionophores but not responses induced by anti-IgE, chemotactic peptide or phorbol ester

1. Galanin concentration-dependently blocked human leukocyte histamine release triggered by the calcium ionophores A23187 and ionomycin. Almost complete inhibition of release was recorded at 410 nM whereas 41 nM galanin mediated close to 50% inhibition of responses. 2. Pretreatment of the cells with pertussis toxin did not influence the inhibitory effects of galanin. 3. Leukocyte responses triggered by anti-IgE, the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP) or 4 beta-phorbol 12-myristate 13-acetate (PMA) were not affected by galanin. 4. Ionophore-induced basophil histamine release, but not responses triggered by anti-IgE, FMLP or PMA, was inhibited when cells were challenged in medium containing high potassium (120mM). 5. We conclude that galanin and a depolarizing medium selectively inhibit ionophore-induced basophil histamine release.

Nimodipine versus terfenadine in the treatment of physical stimulus-induced urticaria

Basophil and mastocyte degranulation is calcium-dependent. Calcium-antagonists can inhibit synthesis of and release in vitro some mediators in various types of cells. Both immunologically stimulated and non-immunologically stimulated release of material from basophils isolated from normal and allergic subjects can be antagonized by calcium blockers. The present study was aimed at testing the therapeutic effects and side effects of nimodipine therapy, a new dihydropyridine anti-calcium derivative for physical stimulus-induced urticaria, in comparison with a standard H1-antihistamine therapy. The study was done in 32 outpatients who had physical stimulus-induced urticaria: 20 patients received nimodipine three times a day in a daily dose of 180 mg, 12 patients were treated with terfenadine in a dose of 120 mg. In the majority of patients treated with both nimodipine and terfenadine, satisfactory clinical results were obtained after 3 weeks of therapy. There were, however significant (P less than 0.05) differences in responses. Complete clearance after 3 weeks was noted in 50% patients treated with nimodipine, whereas only 16% of patients on terfenadine were completely clear, and some showed only slight improvement. The treatment was easily manageable, and with few side effects.