MECHANISTIC APPROACH TO THE EFFECTS OF LOW LEVEL LASER IRRADIATION (LLLI) WITH THE GaAlAs DIODE LASER ON THE PRODUCTION OF REACTIVE OXYGEN SPECIES FROM HUMAN NEUTROPHILS AS A MODEL FOR THERAPEUTIC MODALITY AT A CELLULAR LEVEL

Abstract

There have been many reports on the applications of low reactive level laser therapy (LLLT) for pain attenuation or pain removal. Our group has reported previously on the effects of in vitro low level laser irradiation (LLLI) particularly on the human neutrophil function using luminol-dependent chemiluminescence (LmCL) for measurement of reactive oxygen species (ROS) production from human neutrophils. However, the change in production by LLLI for each ROS e.g. superoxide, hydroxyl radicals, hydrogen peroxide, singlet oxygen, hypochlorite and so on are however not yet fully understood. In this study, we used luminol-dependent and lucigenin-dependent chemiluminescence (LmCL and LgCL, respectively) to measure the effects of LLLI on the ROS-production process of human neutrophils. Two soluble action stimuli, N-formyl-Met-Leu-Phe (fMLP) and phorbol myristate acetate (PMA) were used to avoid the possible influence of lag-time from recognition to uptake of particles at ROS production. When fMLP was used as the stimulus, the maximum intensity of the chemiluminescence response in LmCL increased but in LgCL it decreased following LLLI. When PMA was used as a stimulus, the times to reach the maximum intensity of the chemiluminescence response of LmCL and LgCL were shortened by LLLI but there was no effect on the maximum intensity of the chemiluminescence response of both. These results suggest that LLLI enhances the ROS production capability, and activates the conversion from superoxide to singlet oxygen and hypochlorite.