Polychromatic Light Similar to the Terrestrial Solar Spectrum Without its UV Component Stimulates DNA Synthesis in Human Peripheral Blood Lymphocytes In Vivo and In Vitro

Abstract

Immunosuppressive effects of the minor component of the terrestrial solar spectrum, UV radiation, have been substantiated over the past several years. This raises the question of what influence the dominant part of the solar spectrum--visible and IR light-would have on the human immune system. In the present randomized, placebo-controlled double-blind study a small area of the body surface of volunteers was irradiated with polychromatic light (480-3400 nm), simulating the significant part of the terrestial sunlight irradiance spectrum and its power density. An average 2.5-fold to three-fold increase in spontaneous and phytohemagglutinin-induced DNA synthesis in peripheral blood lymphocytes (Lym) was revealed at 0.5-24 h after irradiation at a therapeutic dose (12 J/cm(2)) in subjects with low preirradiation levels of both processes. The in vivo findings were echoed in parallel in vitro experiments, when blood drawn from the same subjects was directly irradiated (2.4 J/cm(2)), or when the irradiated blood was mixed 1:10 with nonirradiated autologous blood to model events in the circulation following transcutaneous blood photomodification. Our data suggest that exposure of the human body to polychromatic visible + IR light may photomodify blood in the dermal vasculature of the irradiated area to lead to an immediate transfer of the light-induced effects to Lym of the entire circulating blood, which can result in modulation of Lym functional state at the systemic level.

The Effects of Daily Irradiation with Polychromatic Visible Polarized Light on Human Lymphocyte Populations

“…Some recent studies described the changes in expression of membrane markers of human blood mononuclear cells after visible and infrared light (480-3400 nm) irradiation. 31,32 Among the parameters of this study, the absolute count of total lymphocytes and CD3 ϩ CD4 ϩ T cells increased significantly after 28 d of exposure, while the count of CD3 ϩ T cells showed a tendency to increase with borderline statistical significance (p ϭ 0.058). Considering that the total CD3 ϩ T-cell count is the sum of CD3 ϩ CD4 ϩ T cells and CD3 ϩ CD8 ϩ T cells, the most actively increased lymphocyte subgroup was CD3 ϩ CD4 ϩ T cells.…”

“…Taking into account previous studies showing an increase in the T-cell population in peripheral blood after exposure to visible light irradiation, it would appear to be related to stimulation of DNA synthesis and lymphoblastogenesis. 22,31 This finding may suggest that polychromatic visible polarized light stimulates the proliferation of helper T cells and facilitates cell-mediated immune responses.…”

“…[43][44][45] Irradiation with visible and infrared light (480-3400 nm, 12 J/cm 2 ) produced increases in the numbers of T and B lymphocytes and NK cells, except for CD4 ϩ T lymphocytes. 31,32 Visible and infrared light (480-3400 nm, 12 J/cm 2 ) also increased the concentration of the immunosuppressive cytokine interleukin-10, and reduced levels of pro-inflammatory cytokines (TNF-␣, IL-6, and IFN-␥). 29 Visible and infrared polarized light (400-3400 nm) induced a rise in serum IgM and IgA, which suggests B-cell activation.…”

Effect of 710-nm Visible Light Irradiation on Neuroprotection and Immune Function after Stroke

“…The exposure to light of immune-competent cells leads to changes in their functional condition and, consequently, to the stimulation of the immune system, manifesting itself in the increased defense capacity of an organism [17]. VIS and infrared light regulate human humoral immunity [18], manage allergic rhinitis [19], increase antitumor immunity [20] and skin-homing T cells [21], and stimulate DNA synthesis in human peripheral blood lymphocytes [22]. …”

“…Helper T cells activate macrophages and regulate other lymphocytes by inducing various cytokines [23]. The increased T cell population in peripheral blood after exposure to VIS has been shown to be related to DNA synthesis stimulation and lymphoblastogenesis [22]. Immunosuppression after stroke is known to be controlled by regulatory T (Treg) cells, which reduce secondary brain tissue injury and neuroprotection by the inhibition of inflammatory changes and immune reaction [24,25,26,27,28].…”