Hay fever, hives and atopic skin inflammation are all commonly known allergic reactions. In recent years, however, a whole spectrum of illnesses and conditions are now known to actually be types of allergic reactions referred to as autoimmune diseases. These include conditions once classed as skin ailments, such as vitiligo, psoriasis, alopecia areata (autoimmune hair loss), and palmoplantar pustulosis (a form of psoriasis affecting the palms and soles of the feet), to conditions with vastly different symptoms, such as rheumatoid arthritis.

Vitiligo is thought to afflict some 100,000 people in Japan. In this condition, white blood cells lose control and begin attacking melanocytes, the cells that produce pigment for the skin. The attack causes these cells to lose their functionality and to stop making pigment, leading to the condition’s telltale symptoms. Similar attacks on the cells that make up hair follicles in alopecia areata (autoimmune hair loss) and the synovial membrane of the joints in rheumatoid arthritis are the mechanism behind the symptoms associated with these disorders.

Until recently, skin allergy ailments were treated mostly with prescription medication or topical agents. However, concern arose over the limited effectiveness of these approaches, which was often accompanied by unpleasant side effects. UV phototherapy has thus been drawing increasing interest in recent years.

Taking one type of skin allergy, psoriasis, as an example, there are two mechanisms behind how UV phototherapy works. The first is the destruction of the overactive white blood cells, the direct cause of the condition. The second involves increasing the number of a different set of white blood cells, called regulatory T cells, that help deactivate their trouble-causing counterparts. In other words, UV radiation has an immune suppressing effect that reduces the number and attack strength of white blood cells that have begun attacking the body’s own cells, thereby mitigating the symptoms.

A joint research team from USHIO and the Nagoya City University Department of Geriatric and Environmental Dermatology (Prof. Akimichi Morita) decided to tackle the challenge of identifying the optimal treatment. In searching for light that would enhance therapeutic effectiveness with fewer side effects, the team concluded after a detailed analysis of wavelengths that the most effective light is at a wavelength of 308 nm, where effectiveness peaks. They also determined that cutting wavelengths below 297 nm reduced skin redness and other side effects.

While just 3 nm shorter than the 311-nm wavelength conventionally used, there were now grounds to expect that this previously unidentified wavelength could eventually make more effective therapy possible.

The same research team applied their findings to an excimer lamp, a product that USHIO led the world in commercializing in the 1970s. The team developed a light source to emit peak 308-nm wavelength, a technologically impossible task when the lamp was first marketed. The team also successfully developed an excimer filter to block short wavelengths below 297- nm, which were associated with the biggest side effects.

Based on the excimer light, in 2008, USHIO created a working phototherapy device equipped with its own proprietary light technology, making safe and highly effective phototherapy a reality. This was the birth of the TheraBeam_® UV308, the world’s first device of its kind to have both a 308-nm excimer light and excimer filter.

Kobayashi K, Morita A et al, Photoderm Photoimmunol Photomed 25; 30-36, 2009