Circulating CLA+ lymphocytes from children with atopic dermatitis contain an increased percentage of cells bearing staphylococcal-related T-cell receptor variable segments.

Abstract

Atopic dermatitis is an allergic T-cell mediated skin inflammation. Staphylococcus aureus colonization is very common in cutaneous atopic dermatitis lesions. The cutaneous lymphocyte-associated antigen (CLA) is a T cell skin homing receptor that defines T lymphocytes associated with the cutaneous immune response. To study whether CLA+ T cells from atopic dermatitis children present a selective expression for Staphylococcus aureus-related TCR Vbeta segments. Peripheral blood T cells were stained with HECA-452 (anti-CLA) and a panel of TCR Vbeta specific monoclonal antibodies and analysed by flow cytometry. Atopic dermatitis patients have a higher percentage of circulating CLA+ CD3+ lymphocytes compared with healthy controls. Patients with active atopic dermatitis during the study expressed a higher percentage of cells positive for the TCR Vbeta2 and Vbeta5.1 segments in the CLA+ but not in the CLA- subset. These TCR Vbetas are recognized by staphylococcal superantigens. Moreover, there was an increased percentage of HLA-DR+ expression by CLA+ Vbeta5.1+ T cells in patients with active atopic dermatitis, but those patients whose eczema was inactive had very similar values to healthy controls regarding TCR Vbeta and HLA-DR phenotype in circulating CLA+ T lymphocytes. Our data indicate that circulating skin-homing T cells of patients with active atopic dermatitis contain an increased percentage of cells bearing TCR Vbeta segments related with Staphylococcus aureus. Staphylococcus superantigens may therefore trigger expansion or at least circulation of appropriate CLA+ T cells.