The symbiosis of phototherapy and photoimmunology.

The health benefits of natural sunlight have been noted since the rise of civilization, even without the knowledge of its mechanisms of action. Currently, phototherapy remains an effective and widely used treatment for a variety of skin diseases. Ultraviolet radiation, from either the sun or artificial light sources, has a profound immunomodulatory effect that is responsible for its beneficial clinical outcomes. Ultraviolet radiation mostly induces the innate while suppressing the adaptive immune system, leading to both local and systemic effects. It is antigen specific, acts on both effector and regulatory T cells, alters antigen-presenting cell function, and induces the secretion of cytokines and soluble mediators. This review provides an overview of the immunologic mechanisms by which ultraviolet radiation is responsible for the therapeutic effects of phototherapy.

Ultraviolet B radiation therapy for psoriasis: Pursuing the optimal regime.

Psoriasis is a chronic and common disease mediated by resident memory T cells that negatively affects a broad range of people worldwide. One of the oldest and most commonly used treatments is phototherapy. We reviewed the existing literature on the four main ultraviolet B (UVB) modalities of phototherapy in the management of psoriasis: heliotherapy, broadband UVB, narrowband UVB, and excimer laser and lamp. Despite the many studies done on these therapies, there is significant variation in their prescription and use. Phototherapy remains one of the most effective and safest treatments for psoriasis. We provide an updated comprehensive overview of UVB phototherapy for psoriasis to help physicians optimize their choice of modality and dosing regimen to ensure optimal outcomes for psoriasis patients. © 2016 Elsevier Inc. All rights reserved.