Efficacy of a 365nm Ultraviolet A1 light Emitting Diode (UVA1‐LED) in in vitro Extracorporeal Photopheresis

Extracorporeal photochemotherapy (ECP) is one of the more effective cell therapies for graft‐versus‐host disease (GvHD). ECP is a widely recommended therapeutic approach for the treatment of chronic GvHD, particularly steroid‐refractory GVHD. In recent years, the use of a light emitting diode (LED) in the clinic has attracted considerable interest. In this study, we examined the issue of whether an ultraviolet A1‐light emitting diode (UVA1‐LED) can be used as a light source in ECP. To compare the efficacy of ECP with conventional UVA lamp and a UVA1‐LED, we established an in vitro ECP model. Treatment efficacy was evaluated by measuring the % apoptosis and the inhibition of T‐cell proliferation. To investigate the effect of ECP on the innate immune reaction, THP‐1 cells with a luciferase reporter gene driven by a NF‐kB response element (THP‐1 luc NF‐kB) were treated with ECP. The LED‐ECP induced apoptosis and inhibition of T‐cell proliferation as efficiently as a conventional ECP. However, LED‐ECP induced less innate immunity in THP‐1. Since LED devices are more compact compared with conventional UVA irradiation devices, the use of a UVA1‐LED in the treatment of ECP may be a better alternative to conventional ECP therapy.