Ultraviolet B (UVB) is a highly effective, relatively safe, affordable and widely used therapeutic option for moderate
psoriasis. Several types of UVB lamp are available to treat
psoriasis, both broadband and narrowband, allowing a choice of spectral emission. However despite years of clinical use, the mechanism of action of UVB in clearing
psoriasis remained incompletely understood. Moreover, there has been little insight into how the relative effectiveness of different UVB wavelengths linked to the mechanism of action, although it is known that the action spectrum for clearance of
psoriasis differs from the action spectrum of
erythema. This paper examines the existing literature from which our current treatments have evolved, and offers new insight into the use of keratinocyte apoptosis as a
biomarker which may help to optimise UV treatment in the future. When combined with a systems biology approach, this potential
biomarker may provide insight into which wavelengths of UV are the most effective in clearing
psoriasis, allowing a more rational and potentially an individually tailored approach to optimising
phototherapy for
psoriasis.