Effect of linear polarized near-infrared ray irradiation on the chemiluminescence of human neutrophils and serum opsonic activity

The purpose of this study was to investigate the in vitro effects of linear polarized near-infrared ray irradiation on neutrophil chemiluminescence (CL) and serum opsonic activity. We used luminol- and lucigenin-dependent CL to detect the affected reactive oxygen species production process of human neutrophils and measured serum opsonic activity based on luminol-dependent CL. The linear polarized near-infrared ray irradiation suppressed a maximum light emission (peak height) of luminol- and lucigenin-dependent CL in a dose-dependent manner. The findings suggested that the linear polarized near-infrared ray irradiation suppressed the superoxide anion and hypochlorite production of human neutrophils. The serum opsonic activity was decreased by linear polarized near-infrared ray irradiation, and this suppressive effect might be caused by inhibiting the activation of the classical and alternative complement pathway. Therefore, it is suggested that near-infrared ray irradiation may have an inhibitory effect against chronic pain via reduction of reactive oxygen species production and opsonic activity.