Infra-red laser irradiation enhances interleukin-1 receptor antagonist, increases 3H-thymidine incorporation and the release of [3H]arachidonic acid in human monocytes.

The effect of infra-red laser irradiation has been experimented on various biological systems and particularly in human tissues, in vitro as well as in vivo. In order to examine the influence of laser irradiation on cells of the monocytic lineage we have irradiated human peripheral blood mononuclear cells with an infra-red laser at a wavelength of 904 nm, at 2000 Hz frequency and 15 mW for 2 min. Here, we report that laser irradiation for 2 min. at different preincubation times (T = 0 and T = 30 min) enhances LPS (10 micrograms/ml or PHA (10 micrograms/ml, suboptimal concentration)-stimulated monocytes by modifying cell proliferation, as judged by [3H] thymidine incorporation. IL-1 receptor antagonist (IL-1ra) along with an increased release of [3H] Arachidonic acid production, is also influenced by laser irradiated monocytes when treated for 2 min after 1 h incubation. IL-1RA production increased 4-5 fold after laser irradiation, while 3H-arachidonic acid incorporated from PMA-stimulated cells increased and the effect was significant at T = 0 and T = 30 min; while at T = 1 h the effect was negligible. These results may provide new information regarding the effect of laser irradiation on the immune system.