Mechanistic approach to GaAIAs diode laser effects on production of reactive oxygen species from human neutrophils as a model for therapeutic modality at cellular level

Makoto Yamaya*, Chiyuki Shiroto', Hiroki Kobayashi*, Shinji Naganuma*, Jyuichi Sakamoto*, Koh-Jun Suzuki*, Shigeyuki Nakaji*, Kazuo Sugawara* and Takashi Kumae *Department of' Hygiene, Hirosaki University School of Medicine. Hirosaki; .-Shiroto Clinic Coshogawara, Aomori: Department of Industrial Health. The Institute of Public Health, Tokyo. Japan.

There have been many reports on the applications of low reactive level laser (LLL) therapy for pain attenuation or pain removal. Our group has reported previously on the effects of in vitro irradiation of LLLT particularly on the phagocytic activity of human Neutrophils, using luminol-dependent chemiluminescence (LmCL) for measurement of reactive oxygen species (ROS) production from human Neutrophils. However, the mechanisms of the attenuation of phagocytic activity of NEUTROPHILS by LLL irradiation is not yet full understood.

In this study. we used luminol-dependent and lucigenin-dependent chemiluminescence (LgCL) for detection of affected ROS producing process of human Neutrophils by LLL irradiation. Two soluble action stimuli, N-formyl-Met-Leu-Phc (fMLP) and phorbol myristate acetate (PMA) were used to avoid the possible influence of lag-time from recognition to uptake of particles at the ROS production.

In case of using fMLP as a stimulus, the maximum luminescence intensity of LULL was increased hut LgCL luminescence was decreased by LLL irradiation. When PMA was used as a stimulus, the times to reach the maximum luminescence intensity of LmCL and LgCL were shortened by LLL irradiation, but there was no effect on the maximum luminescence intensity of both.

These results suggest that LLL irradiation enhances the ROS production activity of human Neutrophils by the activation of the superoxide converting system, the active clement in which is mainly myeloperoxidase. LLL irradiation enabled a more rapid activation of the superoxide production system, NADPH -oxidase.