Effects of Different Wavelengths of Low Level Laser Irradiation on Murine Immunological Activity and Intracellular Ca²⁺ in Human Lymphocytes and Cultured Cortical Neurogliocytes

Abstract

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The purpose of this study was to determine the wavelength-response effects of low level laser irradiation (LLLI) on immunocompetence of mice in vivo and intracellular free calcium ([Ca²⁺]_i) in human lymphocytes and cultured cortical neurogliocytes (CCN) in vitro. Mice were first immune compromised by cyclophosphamide (CTX) injection, and the immunological activities including the production of interleukin 2 (IL-2), the murine mixed lymphocyte reaction (MLR), the mitogenic response of murine thymocytes (MRT), the proliferation of murine bone marrow cells (BMC) and the natural killer (NK) cells activity, were investigated after intravascular low level laser irradiation (ILLLI) (1 mW, 1.1×10⁴ J/cm²) at wavelengths of 532 nm, 632.8 nm, 650 nm and 1520 nm, respectively. In addition, using Ca²⁺ sensitive indicator Fura-2 AM with the Spex AR-CM-MIC cation measurement system ([Ca²⁺]_i) in single human lymphocytes and CCN were measured after LLLI (7.5 J/cm²) at wavelengths of 532 nm, 632.8 nm, 650 nm, 810 nm and 1300 nm, respectively. Results showed that the ILLLI at wavelengths of 532 nm, 632.8 nm and 650 nm, produced a significant increase in the proliferation of BMC and the NK activity. The production of IL-2 was greatly promoted after irradiation at 632.8 nm and 650 nm. After irradiation at 532 nm and 650 nm, the murine MLR was evidently enhanced, and MRT was dramatically increased only after irradiation at 632.8 nm. In contrast, no significant effects were found on the above mentioned indexes by irradiation at 1520 nm in comparison to the control. In addition, [Ca²⁺]_i in single human lymphocytes and CCN were increased after LLLI at wavelengths of 532 nm, 632.8 nm and 650 nm, respectively, whereas they were not significantly affected by the wavelengths of 810 nm and 1300 nm. Our results indicated that LLLI could induce significant and different effects on the immunological activities of the mice and cause an increase in [Ca²⁺]_i in single human lymphocytes and CCN. Furthermore, these effects are dependent on the wavelengths, for example, more positive effects produced by the wavelengths of 532 nm, 632.8 nm and 652 nm than those produced by the wavelengths of 810 nm, 1300 nm and 1520 nm.