Biomolecular regulation of the IgE immune response III. Cytokine profiles in atopic dermatitis, inhalant allergy and non-allergic donors.

Cytokines-in particular interleukin 4 (IL-4), IL-5 and interferon gamma (IFN-gamma)-regulate both IgE synthesis and eosinophil activation in atopic diseases. To elucidate whether distinct profiles of cytokine production were related to serum level of IgE and eosinophilia, the spontaneous and inducible in vitro cytokine secretion from peripheral blood mononuclear cells (PBMC) was investigated. PBMC were isolated and cultured from three groups of donors: (1) patients with atopic dermatitis (AD) and high levels of serum IgE (> 5000 IU/ml, n = 11), (2) patients with diagnosed inhalant allergy (IA) and serum IgE in the range of 200-2000 IU/ml (n = 10), and (3) non-allergic individuals (NA) with serum IgE below 100 IU/ml (n = 10). The production of cytokines was determined in cultures after 24 h [IL-1 alpha, IL-4, IL-5, IL-6, tumour necrosis factor alpha (TNF-alpha), and TNF-beta] or 72 h (IL-2, IFN-gamma). The spontaneous production of IL-1 alpha was increased in the AD group compared to NA (P = 0.002), whereas for unstimulated cultures no other cytokine differed between patient groups. To identify conditions for optimal cytokine production, various combinations of phytohaemagglutinin (PHA), calcium ionophore (ION), and phorbol ester (PMA) were tested as stimuli. The combination ION + PMA induced the highest levels of IL-2, IL-4, IL-5, IFN-gamma and TNF-alpha, whereas maximal production of IL-6 and TNF-beta were induced by PHA and PHA + PMA, respectively. The AD group demonstrated a significantly lower production of TNF-alpha and IFN-gamma compared with the two other groups, and IL-4 and IL-5 production increased in the IA group. The results suggest that in spite of the common features, i.e. raised serum IgE and eosinophilia, in IA and AD patients, the underlying aberrations in the cytokine network is different.