Ultraviolet A1 (340-400 nm) irradiation and systemic lupus erythematosus

Short wavelengths of ultraviolet (UV) light are clearly harmful in systemic lupus erythematosus (SLE), but the action of long UV wavelengths in SLE is more enigmatic. In a series of animal and human studies, long-wavelength U V radiation, i.e., radiation in the ultraviolet-A1 (UVA1) range (340-400 nm ), has proven effective in the treatment of SLE. Disease amelioration and a marked decrease in mortality followed ultraviolet-A (UVA) radiation (320-4 00 nm) of the New Zealand White/New Zealand Black mouse model of lupus, A f ollow-up study in the same animal suggested that the longer wavelengths (UV A1, 340-400 nm) in the WA wave band were primarily responsible. There follo wed four human studies. The first three of these provided data indicating t hat low-dose UVA1. radiation significantly reduced constitutional symptoms, joint pain, rashes, and the systemic lupus activity measures, a validated gauge of disease activity in SLE, The fourth human study showed that the th erapeutic action of low-dose UVA1 action persisted or progressed long term, a period averaging 3.4 y, UVA1 effects on DNA repair, cell-mediated immuno suppression, tumor necrosis factor alpha release, and apoptosis contrast ma rkedly with those of ultraviolet B (UVB, 280-320 nm) radiation and afford a possible basis for the salutary action of this modality of treatment, The unique features of UVA1 wavelengths may be suited to further therapeutic us e, not only in SLE but also in other immunologic disorders.