Decreased frequency of interferon-γ-producing CD4⁺ cells in the peripheral blood of patients with atopic dermatitis

Recently, decreased interferon-γ (IFN-γ) and increased interleukin (IL)-4 production have been reported in measurements of the content of the cytokines in culture supernatants of peripheral blood mononuclear cells (PBMC) obtained from patients with atopic dermatitis (AD). These data suggest deviation of PBMC into Th₂-reactive cells in AD. In the present study, we examined the frequency of IL-2-, IL-4-, and IFN-γ-producing cells in PBMC with flow cytometry. PBMC from 16 patients with AD and 18 healthy controls were stimulated for 2 days with anti-CD3 and IL-2, and further cultured for 4 days with a maintenance dose of IL-2. Thereafter these cells were restimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin for 4 h in the presence of monensin. After fixation of the cells, the cell membranes were made permeable and intracellular cytokines were stained with anti-IL-2, anti-IL-4 or anti-IFN-γ antibody. Cytokine-producing cells were analyzed by gating CD4⁺- or CD8⁺-subsets. Thus counted frequency of IFN-γ-producing cells was significantly decreased in CD4⁺ subsets of AD patients (9.9±7.4%) when compared with that in the controls (20.0±6.7%). There was no significant difference either in the frequency of IL-2- or IL-4-producing CD4⁺ subsets or in that of CD8⁺ subsets. Furthermore, in the enzyme-linked immunosorbent assay, we also found a decreased production of IFN-γ in the culture of PBMC from AD patients, when compared with those from healthy controls, although it was only at a marginally significant level (P=0.07). Again there was no increase in IL-4 concentration in AD patients. In addition, we found a weak negative relationship between the disease severity and the frequency of these cells. These results suggest that the decreased frequency of IFN-γ-producing CD4⁺ cells with subsequently decreased production of IFN-γ play a crucial role in the pathophysiology of AD.