Isolation of type 1 and type 2 cloned mite allergen-specific T cells from an asthmatic child

Both allergen-specific CD4 and CD8 Type 2 T cells decreased in asthmatic children with immunotherapy

Allergen-specific immunotherapy (IT) has been used for the treatment of atopic diseases since the turn of this century. The precise working mechanisms, however, remain to be clarified. The aim of this study was to investigate the role of particular subsets of allergen-specific T cells in the non-atopic individuals, untreated asthmatic children and the asthmatic children receiving immunotherapy. We collected peripheral blood from 16 untreated asthmatic children and 17 asthmatic children receiving immunotherapy over one and half years. All the patients were sensitive to mite allergen. Peripheral blood mononuclear cells (PBMC) were isolated and, in vitro, stimulated with crude mite extract to enrich the mite-specific T-cell population. After 14 days, the enriched mite-specific T cells were stimulated with phorbol-12-myristate-13-acetate (PMA) and ionomycin for intracellular detection of cytokines such as IFN-gamma, IL-4 in CD4+ and CD8+ T lymphocytes. The data here demonstrated that the levels of mite-specific IgG4 and IgA increased significantly in asthmatic children after immunotherapy. In addition, both IL-4 expressing CD4+ and CD8+ T cells were significantly lower in asthmatic children after immunotherapy compared with those of before treatment and the normal control (p < 0.05). In contrast, the frequency of IFN-gamma expressing CD4+ and CD8+ T cells did not significantly differ between untreated and SIT-treated groups. All these data suggested that decreased Type 2 CD4+ and CD8+ T cells might be closely correlated with the regulatory mechanisms of immunotherapy.

Beta2-agonist exerts differential effects on the development of cord blood T cells but not on peripheral blood T cells

Asthma is a chronic inflammatory disease characterized by reversible airway obstruction caused by edematous airway lining, thickened mucosal secretions, and smooth muscle constriction. Beta2-adrenoceptor agonists are widely used in the treatment of bronchial asthma because of their ability to induce relaxation of airway smooth muscle. Evidence indicates that desensitization and down-regulation of beta-adrenoceptors occurs in long-term beta2-agonist therapy, and these medications were thought to cause increased severity of, and mortality in, asthma. The purpose of this study was to delineate further the potential adverse effects of beta2-agonists on the development of T lymphocytes. T cells isolated from umbilical cord blood and adult peripheral blood were cultured in the presence of salbutamol. Intracellular staining with fluorescence-labeled antibodies was used to differentiate the frequency of type 1 T-helper (Th1) and type 2 T-helper (Th2) cells. The results showed a statistically significant inverse relationship between the concentration of salbutamol and the ratio of Th1 over Th2 on cord blood T cells. However, this trend was not observed in adult peripheral blood T cells. The data revealed another potential adverse effect in which chronic beta2-agonist exposure predisposed differentiation of T lymphocytes towards Th2 while that of Th1 was relatively suppressed, especially in cord blood T cells. Hence, beta2-agonists, despite their effect in symptomatic rescue in asthma, should not be used indiscriminately as long-term therapeutic agents.

Administration of interleukin-12 exerts a therapeutic instead of a long-term preventive effect on mite Der p I allergen-induced animal model of airway inflammation

Interleukin-12 (IL-12) is a key cytokine, which promotes T helper type 1 (Th1) cell-mediated immunity and inhibits Th2-type responses. It has been previously shown that IL-12 administration during active immunization following a single allergen exposure can prevent antigen-induced increases in immunoglobulin E (IgE) formation, Th2 cytokine production and bronchoalveolar lavage (BAL) eosinophils in a murine model of allergic airway inflammation. Thus, these studies have now been extended and two IL-12 treatment protocols on this murine model were evaluated. Administration of IL-12 during the active immunization strikingly increased Der p I-specific serum IgG2a and transiently decreased the levels of IgG1 and IgE antibodies following multiple allergen challenges. Such early treatment of IL-12 down-regulated IL-5 production and modestly up-regulated interferon-gamma production but did not effect BAL eosinophilia. These results suggest that repeated exposure to antigen and IL-12 is necessary to maintain a persistent Th1-recall response. Furthermore, administration of IL-12 to actively immunized mice, in which Th2-associated responses were established, had a significant effect on IgG2a synthesis and a modest effect on IgE levels, also down-regulation of IL-5 production, and markedly increased interferon-gamma production and abolished recruitment of eosinophils. Therefore, these data indicate that IL-12 can inhibit antigen-induced eosinophil infiltration into airways, despite the existence of a Th2-associated response. Taken together, these studies suggest that IL-12 may be useful as an immunotherapeutic agent in the treatment of such pulmonary allergic disorders as bronchial asthma.

Administration of interleukin-12 prevents mite Der p 1 allergen-IgE antibody production and airway eosinophil infiltration in an animal model of airway inflammation

The aim of the present study was to examine the in vivo effect of interleukin (IL)-12 on a murine model of asthma induced by Dermatophagoides pteronyssinus-derived Der p 1 allergen. C57BL/6 mice immunized with Der p 1 allergen adsorbed to alum/pertussis toxin developed a T-helper type 2 (Th2)-dominant immune response characterized by the presence of IgE antibody, airway eosinophil infiltration and increased production of Th2 cytokine. Intraperitoneal injection of IL-12 (1 or 0.1 microg per day) for 5 days (day -1 to +3) simultaneously with each immunization, inhibited the production of IgE and IgG1 antigen-specific antibodies, whereas production of IgG2a was strongly enhanced. In addition, mice receiving both doses of IL-12 showed a strong inhibition of IL-5 but up-regulation of IFN-gamma production by spleen cells stimulated with antigen. Administration of IL-12 also prevented antigen-induced eosinophil infiltration into the bronchoalveolar area in a dose-dependent manner and the primary inflammatory mediator serotonin in bronchoalveolar lavage (BAL) fluids was also reduced significantly. Taken together, the data indicate that IL-12 has a potent immunomodulatory effect on house-dust-mite-induced allergic disorders and may be used as an efficient agent for immunotherapy.