Effects of weak laser radiation (632.8 nm) on isolated mouse immune cells

The dose dependence of in vitro effects of low-intensity radiation of a He-Ne laser (632.8 nm, 0.2 mW/cm2) on the functional activity of peritoneal macrophages and lymphocytes of mouse spleen was studied. The exposure of isolated cells was varied from 5 to 180 s. If the exposure did not exceed 60 s, stimulation of secretory activity was observed: increased production of interleukin 2, interferon γ, and interleukin 6 in lymphocytes; increased production of tumor necrosis factor α, nitric oxide, and interleukin 6 in macrophages; and enhanced activity of natural killer cells. A longer exposure (up to 180 s) either had no effect on the synthesis of certain cytokines (interleukin 2 in lymphocytes and interleukin 6 in macrophages) or inhibited it, which was expressed in decreased production of interleukin 6 and interferon γ in lymphocytes and nitric oxide in macrophages, as well as in suppression of the activity of natural killer cells. Conversely, the production of interleukin 3 decreased after a short-term exposure but increased after 180-s irradiation. The high sensitivity of cells to extremely weak laser light also manifested itself as a considerable increase in expression of the inducible heat shock protein 70; this effect was observed at all doses studied, including the 5-s exposure. In contrast, expression of the heat shock protein 90 slightly decreased after irradiation of cells with laser light. © Nauka/Interperiodica 2006.