Effects of 660 nm red light and 850 nm near infrared light on human blood lymphocytes

Abstract The applications of light emitting diodes (LED) as a red light therapy (RLT) source for the management of various conditions such as wound treatment, control of inflammation and pain have been growing continually. Despite its extensive medical application, the effects of RLT on living cells are still highly contested. This study is conducted to test the effects of RLT using combined LED source with 660 nm (red) and 850 nm (near infrared) light on cultured human lymphocytes in vitro. To analyze the effect of RLT on human peripheral blood lymphocyte’s proliferation, the mitotic index (cytostatic effect) is monitored under different irradiation exposure time parameters and conditions. This value indicates how a particular treatment affected cell division, either proliferatively, inhibitory, or had no effect at all. The interpretation of the results of the mitotic index is done in relation to the mitotic index of the untreated (unirradiated) control cells. Our data shows higher lymphocyte proliferation for all of the irradiated samples, and is particularly enhanced by multiple exposures to red light. The effectiveness of RLT on cell activity is of importance in determination of suitable treatment for diseases related to the immune system. To better understand the molecular and metabolic mechanisms involved in red LED-induced photobiomodulation, the study will be extended to investigate the RLT effect on cell protein synthesis.