Light therapy (with UVA-1) for SLE patients: is it a good or bad idea?

The development of skin rash—an unusual reaction to sunlight—is one of the criteria used in the diagnosis of systemic lupus erythematosus (SLE). In addition, exposure to sunlight is a risk factor for the induction or exacerbation of the disease. Patients with SLE who regularly protect themselves against sunlight appear to have significantly less renal involvement, thrombocytopenia, hospitalization and requirement for cyclophosphamide treatment [1]. All these facts support the importance of photoprotection in patients with SLE and suggest that light therapy in SLE patients may be more detrimental than beneficial. However, in 1987 McGrath and co-workers [2] reported that long-wave ultraviolet (UV) radiation had a favourable effect on disease activity in SLE model mice. These rather unexpected results were later confirmed in a group of SLE patients [3]. Until now, there have been only a few clinical trials investigating this new therapeutic approach. They have all shown, however, that repeated whole-body exposure to the long-wave UV (UVA-1) can reduce disease activity in SLE patients [4–6]. In our recent work we suggested that UVA-1 could be used as an adjuvant therapy for SLE [7]. Thus, it appears that light therapy does not have to be a bad idea at all if the patients are exposed to selected wavelengths of the solar spectrum.