CD28 and secretory immunoglobulin A-dependent activation of eosinophils: inhibition of mediator release by the anti-allergic drug, suplatast tosilate.

BACKGROUND: Eosinophils are major effector cells in allergic diseases. After their recruitment to sites of inflammation, they contribute to the pathophysiology of the disease by releasing granule proteins and cytokines. Suplatast tosilate (IPD-1151T), a new anti-allergic agent, has shown beneficial effect in the treatment of asthma, associated with reduced bronchoalveolar lavage eosinophil infiltration and eosinophilic cationic protein (ECP) release in serum and sputum. OBJECTIVE: We investigated whether suplatast tosilate could exert direct effects on human eosinophil activation. METHODS: Eosinophils from hypereosinophilic patients or normal donors were purified by Percoll gradient and the magnetic cell separation system. Chemotaxis was studied using the Boyden chamber technique using three chemoattractants, formyl-methionine-leucine-phenylalanine (fMLP), IL-5 and eotaxin. Oxidative metabolism was determined by a luminol-dependent chemiluminescence assay after activation with eotaxin or secretory IgA (sIgA). The release of ECP and eosinophil derived neurotoxin (EDN) was measured by radioimmunoassay and cytokine production was determined by ELISA following activation with sIgA or anti-CD28. RESULTS: The chemotactic response to fMLP, IL-5 and eotaxin was significantly inhibited by IPD-1151T. Suplatast tosilate was partially inhibiting the release of reactive oxygen species (ROS) induced by eotaxin and sIgA. Activation by sIgA and CD28 ligation resulted in the release of ECP and EDN, which was inhibited by IPD-1151T. Upon activation by anti-CD28, only IL-13 production was inhibited by IPD-1151T, whereas release of IL-2 and IFN-gamma was not affected. IL-10 release induced by sIgA was also inhibited by IPD-1151T. Additionally, the pro-inflammatory cytokine IL-6, which was secreted following anti-CD28 and sIgA stimulation, was strongly inhibited by IPD-1151T. CONCLUSION: Through inhibition of chemotaxis, IPD-1151T might limit the number of eosinophils at the inflammation site. Furthermore, it could reduce the pathological potential of eosinophils by inhibiting the release of ROS and cationic proteins, main inflammatory mediators produced by eosinophils. Moreover, the inhibition of immunoregulatory cytokines released by eosinophils could locally modify the immune response.

The inhibitory effect of anti-allergic agent suplatast tosilate (IPD-1151T) on methacholine- and allergen-induced bronchoconstriction in sensitized mice. asakazu@med.showa-u.dc.jp.

The influence of an anti-allergic agent, suplatast tosilate (IPD-1151T; (+/-)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenyl-carbamoyl]-ethyl] dimethylsulfonium p-toluenesulfonate) on allergic bronchoconstriction induced by allergen and methacholine (MCh) were examined in mice. BALB/c mice were sensitized by intraperitoneal injection of dinitrophenylated-keyhole limpet hemocyanin (DNP-KLH) mixed with A1(OH)3 (DNP-KLH). IPD-1151T was administered orally once a day for either 5 or 14 days in doses of 10, 30 or 100 mg/kg. Bronchoconstriction was measured 24h after the final drug administration. IPD-1151T inhibited both antigen- and MCh-mediated bronchoconstriction in actively sensitized mice. The inhibition induced was closely related to the dose and frequency of oral administration of the agent. We also examined the effect of IPD-1151T on IgE production in response to DNP-KLH immunization. IPD-1151T inhibited dose-dependently both total and specific IgE concentrations in serum prepared from mice 15 days after immunization. These results strongly indicate that IPD-1151T inhibits IgE production in vivo and results in attenuating effect on bronchoconstriction.

[Antigenicity tests of suplatast tosilate (IPD-1151T)].

Antigenicity of suplatast tosilate (IPD-1151T) was investigated in guinea pigs and mice. The results were as follows: 1. Homologous passive cutaneous anaphylaxis (PCA), active systemic anaphylaxis (ASA), active cutaneous anaphylaxis (ACA) and Schultz-Dale reaction tests were carried out using guinea pigs which were immunized orally with IPD-1151T alone or subcutaneously with IPD-1151T and Freund's complete adjuvants (CFA). Positive reactions in these tests were not produced by eliciting injection of IPD-1151T or its metabolite, M-1. On the other hand, the sensitization of ovalbumin (OVA) with CFA produced positive reactions in all of PCA, ASA, ACA and Schultz-Dale tests. 2. Heterologous passive cutaneous anaphylaxis (PCA) test using rats was carried out using two strains of mice (C3H/He and BALB/c) which were immunized orally with IPD-1151T alone or intraperitoneally with IPD-1151T and aluminum hydroxide gel (Alum) as an adjuvant. No animals showed positive reaction to both eliciting antigens, IPD-1151T and M-1. On the other hand, a positive reaction in PCA test to eliciting antigen, OVA, was obtained in rats treated with sera of mice sensitized with OVA plus Alum. 3. These findings showed that IPD-1151T had no antigenicity in guinea pigs and mice.

Dogger bank itch. 4. An eczema-causing sulfoxonium ion from the marine animal, Alcyonidium gelatinosum [Bryozoa].

Repeated exposure to the marine bryozoan, Alcyonidium gelatinosum, frequently provokes an eczematous allergic contact dermatitis known as the "Dogger Bank Itch". The dermatitis, representing a severe occupational disease, is especially widely distributed among trawlermen working in the Dogger Bank area in the North Sea. The allergy is shown to belong to the type of cell-mediated hypersensitivity. The hapten has been identified as the (2-hydroxyethyl)dimethylsulfoxonium ion. The isolation, structure determination and synthesis are discussed.