Search

Here, we investigated whether an anti-allergy drug, terfenadine, affects interleukin-4-modulated cytokine expression in peripheral T cells. Peripheral blood T cells were first stimulated with recombinant interleukin-4 and then tested for modulation of the mRNA of a panel of cytokines using the reverse transcription-polymerase chain reaction followed by Southern blot analysis. It was found that T cells constitutively expressed mRNA specific to T helper 1 cytokines (interleukin-2, interferon-gamma, tumor necrosis factor-alpha), which was markedly downregulated upon stimulation with interleukin-4, whereas mRNA for T helper 2 cytokines such as interleukins 4, 5, and 6 was induced in response to interleukin-4. Interestingly, the interleukin-4-induced expression of all T helper 2 cytokines examined was markedly downregulated by terfenadine. Among T helper 1 cytokines, interleukin-4-mediated suppression of tumor necrosis factor-alpha was not affected by terfenadine, which, however, markedly restored mRNA expression of interferon-gamma or interleukin-2. Electrophoretic mobility shift assays using [32P]-labeled synthetic oligonucleotides encoding the consensus binding motif of activator protein-1 demonstrated that interleukin-4-induced binding of activator protein-1 composed of JunB was interfered by terfenadine. This study indicates that terfenadine, at least partially, interferes with interleukin-4-activated signaling, leading to terfenadine antagonism against the modulatory impact of interleukin-4 on T cell cytokines.

Atopic dermatitis is regarded as mediated by Th2-type immunity. In fact, it frequently coincides with the elevation of immunoglobulin (Ig)-E in patients' sera. Due to the pivotal role of interleukin (IL)-4 in regulation of IgE, we hypothesized if atopic dermatitis represents a hyper-reactive condition in response to IL-4 when it coincides the higher serum level of IgE. To address this possibility, peripheral blood mononuclear cells (PBMC) isolated from patients with atopic dermatitis with the high serum IgE level, from those with psoriasis or from healthy volunteers were stimulated with recombinant IL-4 and analyzed for activation of transcription factors including activator protein (AP)-1 or signal transducers and activators of transcription (STAT)-6 by employing electrophoretic mobility shift assays. Although no significant difference between atopy patients and other groups was observed in the STAT-6 binding activity in IL-4-stimulated PBMC, it over-activated the binding of AP-1 in PBMC of the patients with atopic dermatitis. The AP-1 binding was interfered by the use of an antibody directed against JunB. This is the indication that IL-4-overactivated AP-1 is composed of JunB. Furthermore, semi-quantitative RT-PCR analyses revealed marked down-modulation of a Th1 cytokine, interferon (IFN)-gamma, in IL-4-stimulated PBMC derived from atopy patients, but not that from healthy individuals. Together, our present study indicates that AP-1 is over-activated by IL-4 in PBMC of the atopic patients with the higher IgE level, thereby implying that IL-4-induced over-activation of AP-1 might be one of pathogenic factors in atopic dermatitis.