CD30 expression on circulating memory CD4⁺ T cells as a Th2-dominated situation in patients with atopic dermatitis

Th2 clones have been reported to express CD30 preferentially, but whether T cells producing Th2-type cytokines may favor CD30 expression in the in viva state remains unknown. We investigated the expression of CD30 on circulating T cells in atopic dermatitis (AD) as a Th2-dominated disorder. Peripheral blood mononuclear cells were prepared from 51 AD patients and 14 nonatopic controls, and their phenotypes were analyzed with flow cytometry. Cytokine production by stimulated CD4⁺ T cells was also assessed by the single-cell-staining method. Flow cytometric analysis clearly revealed that CD30⁺ T cells were identifiable in the blood of AD patients with greater frequency compared to controls. The important finding was that CD30 expression was restricted to a small but substantial population of memory (CD45RO⁺) CD4⁺ T cells, but not CD8⁺ ones. In AD patients, it was demonstrated that the percentages of CD30⁺ cells within CD45RO⁺ CD4⁺ T cells correlated well with the disease severity, serum IgE levels, peripheral eosinophil counts, and tendency toward Th2-dominant cytokine pattern as determined by the ratio of interleukin-4 to interferon-gamma production. This study suggests that CD30 expression in circulating T cells might serve as an in viva marker for the Th2-dominated condition.