Opposing effects of UVA1 phototherapy on the expression of bcl-2 and p53 in atopic dermatitis

Recently, medium-dose UVA1 phototherapy (50 J/cm(2)) has been introduced as an effective treatment for severe atopic dermatitis (AD). In order to furt her elucidate the mechanisms by which medium-dose UVA1 irradiation leads to an improvement in skin status in patients with AD, biopsy specimens from t en patients before and after treatment were analysed immunohistochemically for features of apoptosis. We sought to determine the extent to which UVA1 irradiation was able to modulate the balance between p53 and bcl-2 expressi on in vivo using monoclonal antibodies labelling these proteins. As compare d with lesional skin of patients with AD before UVA1 irradiation, the numbe r of dermal cells, apparently lymphocytes, that Here positive for p53 had s ignificantly increased after treatment and, in addition, some basal keratin ocytes showed slight positive staining for p53. An increased expression of the bcl-2 gene before treatment in predominately dermal lymphocytes was sig nificantly downregulated by UVA1 therapy. The increase in p53(+) cells and the decrease in bcl-2(+) cells were closely linked to a significant reducti on in dermal T cells (CD3(+)) and a substantial clinical improvement in ski n condition. In summary, medium-dose UVA1 irradiation led to a marked modul ation of the expression of p53 and bcl-2, and this plays a key role in regu lating UVA1-induced apoptosis.