Suppression of IgE production by IPD-1151T (suplatast tosilate), a new dimethylsulfonium agent: (2). Regulation of human IgE response

Suppression of human immunoglobulin E antibody production by a new naphthalene derivative

A new naphthalene derivative, (E)-2-(7-(2-naphthyl)-6-heptenamide)benzoic acid (TEI-8364) was assessed for its effect on interleukin (IL)-4- and anti-CD40 monoclonal antibody-induced immunoglobulin E (IgE) production by cultured human lymphocytes. TEI-8364 preferentially suppressed the production of IgE by peripheral blood mononuclear cells (PBMC) in a dose-dependent manner, without inhibiting PBMC proliferation. In addition, TEI-8364, at a concentration of 10 microM, completely inhibited IL-4- and anti-CD40-induced IgE production by purified tonsillar B lymphocytes, suggesting that TEI-8364 affects B cells by interfering with signals provided by IL-4 or through CD40 and IL-4. TEI-8364 also had a profound inhibiting effect on the in vitro production of specific antibody to a T cell-dependent antigen by PBMC from an immunized volunteer, cultured in the presence of antigen. Furthermore, TEI-8364 at a dose of 1 mg/mouse/day selectively inhibited IgE production by severe combined immunodeficiency mice engrafted with human PBMC, if the drug was administered subcutaneously for five consecutive days. These findings suggest that TEI-8364 is a potent therapeutic agent that may be useful in the treatment of IgE-mediated allergic disorders.

Down-regulation of Th2 cell-mediated murine peritoneal eosinophilia by antiallergic agents

Local eosinophilia has been linked to the pathogenesis of the inflammatory aspect of allergic diseases. The present study found that co-injection of D10G4.1 (D10) cells, a murine Th2 clone, with conalbumin (CA) into the peritoneal cavity of AKR/J mice increased the number of peritoneal eosinophils. The accumulation of eosinophils reached a maximum level at 24 to 48 hr and was accompanied by a marked increase in the number of neutrophils and a minor increase in the number of mononuclear cells. D10-induced peritoneal eosinophilia was suppressed by administration of either anti-IL-4 and anti-IL-5 monoclonal antibodies in an additive manner or by cyclosporin A (CsA). Interestingly, suplatast tosilate (IPD-1151T), known to be antiallergic agent capable of suppressing IgE synthesis and chemical mediator release, but not disodium cromoglycate, selectively suppressed eosinophil accumulation. Taken together with the observation that CsA and IPD-1151T suppressed IL-4 and IL-5 production by CA-stimulated D10 cells in vitro, the present results strongly suggest that agents capable of down-regulating Th2 cell cytokine production may attenuate allergic inflammation by impairing the recruitment of eosinophils that is mediated by Th2 cells.