The effect of phototherapy on neutrophils.

BACKGROUND The role of phototherapy on neutrophils has not been reviewed previously. This novel and non-invasive therapeutic approach is of particular interest for potential use in the treatment of pathologic processes in dermatology and infectious diseases in which neutrophils are the primary culprit. OBJECTIVES The primary aim of this study was to systematically review the role of phototherapy on neutrophils. METHOD Original publications were identified through searches in PubMed, Medline, Ovid, and the Cochrane Library. Search terms used included "phototherapy and neutrophils," "light therapy and neutrophils," and "laser and neutrophils." Studies were selected based on the level of evidence-based research. RESULTS The literature search revealed a total of 22 controlled laboratory studies that evaluated the role of phototherapy on neutrophils. Among the effects of phototherapy noted were increases in: the respiratory burst of neutrophils, apoptosis of polymorphonuclear cells, and plasma NO and iNOS mRNA. Other notable findings include decreased: number of neutrophils in areas of inflammation, ROS production, neutrophil anti-apoptotic factors, and IL-1beta concentration. Studies on PDT demonstrated neutrophilia and resultant decreased tumor growth. CONCLUSION Evidence indicates that phototherapy has a significant impact on neutrophils, the effect of which varies according to the specific type of phototherapy. These findings have a variety of potential clinical applications including the treatment of various autoimmune conditions, inflammatory diseases, and cancers.