T-cell subsets in acne rosacea lesions and the possible role of Demodex folliculorum.

Skin biopsy specimens from 4 patients with typical acne rosacea lesions were examined for the presence of T-cell subsets using monoclonal antibodies. The infiltrates consisted chiefly of LEU-1 reactive T cells with a predominance of LEU-3a antibody positive helper-inducer T cells, while LEU-2a staining suppressor-cytotoxic T cells were scarce. These cells penetrated regularly into the follicular wall and the epidermis. The study showed that most T cells in the dermal granulomatous infiltrates around Demodex parts, which were displaced extrafollicularly, were helper-inducer T cells. The predominance of helper-inducer T-cell subsets in the dermal infiltrates of acne rosacea lesions in frequent association with Demodex supports the hypothesis that a cell-mediated immune response plays an important role in the pathogenesis of rosacea.