Irradiation of light emitting diode at 850nm inhibits T cell-induced cytokine expression

Abstract

Background: An anti-inflammatory effect of light obtained from light-emitting diodes (LEDs) has been discovered, however, limited ranges of wavelengths have been used and the action mechanism has been rarely demonstrated.

Objective: We sought to analyze the immunomodulatory effect of LED on Jurkat T cells and human T cells.

Methods: Jurkat T cells with/without stimulation were irradiated once or five times using seven ranges of LED wavelengths, from 415nm to 940nm. Cytotoxic effects were examined by an MTT assay. Changes in T cell-induced cytokines, including IL-2, IL-4, IL-10, IL-12 and IFN-gamma, and their upstream signaling molecules, ZAP-70 and PKCθ, were examined by real-time PCR, ELISA, and Western blot analysis. The effect of the LED wavelength, whose effect was identified on Jurkat T cells, was also examined in human CD3+ T cells with/without stimulation and in Dermatophagoides farinae-induced atopic dermatitis (AD) NC/Nga mice.

Results: Lower doses of LED irradiation at 850nm inhibited T cell-derived cytokines without inducing cell death in both Jurkat T cells and human T cells. Repeated exposure resulted in a greater increase of inhibitory effects than that observed with a single exposure, and these effects were identified in the NC/Nga AD model.

Conclusions: Although more remains to be clarified, these results may support the clinical application of LED for immune regulation.