An increasing numberof studies have continued to examine the effects of low intensity lasers on the immune system.The 1982 study of Kupin et al constitutes a pioneering effort in this direction. In this study, T and B lymphocytes separated from heparinized blood samples from 30 breast cancer or melanoma patients,and 20 normal donors were irradiated in vitro with argon laser (wave lengths 488 and 514 nm) and He-Ne laser

(wave length 633 nm) at a power of 30 ~ m for- va~rying periods of 3, 5, and 10 minutes. After 1, 2, 3, 4, 5, and 24 hours, respectively, the percentage of rosette-forming cells was determined. Results showed an increase in the percentage of active T-cells particularly in patients with a suppressed immune system. lmmunofluorescence studies also showed increasedpotentiationof the rosette- forming activity of both T and B lymphocytes regardless of the wavelength of the laser.

Here is alist of some other old studies od immunomodulating effects of laser light

•Duan R, Liu C-Y, Li Y, et al. Signal transduction pathways involved in low intensity He Ne laser induced respiratory burst in bovine neutrophils: a potential mechanism of low intensity laser biostimulation. Lasers in Medicine and Surgery. 2001. 29: 174-178.

•Schindl L et al. Effects of low power laser irradiation on differential blood count and body temperature in endotoxin preimmunized rabbits. Life Science. 1997. 60(19 : 1667-1669.

•Inoue K et al. Suppressed tuberculin reaction in guinea pigs following laser irradiation. Lasers in Surgery and Medicine. 1989. 9: 271-275.

•Funk J O, Kruse A, and Kirschner H. Cytokine production after helium-neon laser irradiation in cultures of human peripheral blood mononuclear cells. J Photchem Photobiol B. 1992. 16(3-4): 347-355.

•Katsuyama I et al. Suppressive effect of diode laser irradiation on picryl contact sensitivity. Laser Therapy. 1998. 10(3): 117-122.

•Yu W et al. Improvement of host response to sepsis by photobiomodulation. Lasers in Surg Med. 1997. 21: 262-268.

•Fujimaki et al (Fujimaki Y, Shimoyama T, Liu Q, Umeda T, Nakaji S, and Sugawara K. Department of Hygiene, Hirosaki University School of Medicine, Japan. Low-level laser irradiation attenuates production of reactive oxygen species by human neutrophils. J Clin Laser Med Surg. Jun 2003. 21(3): 165-170.)

conducted a study to examine the effects of low-level laser therapy (LLLT) on production of reactive oxygen (ROS) species by human neutrophils. LLLT is an effective therapeutic modality for inflammatory conditions. An infrared diode laser (GaAlAs), 830-nm continuous wave (150 mW/cm2) was used for treatment). After irradiation, ROS production by neutrophils was measured using luminol-dependent chemiluminescence (LmCL) and expression of CD11b and CD16 on neutrophil surface was measured by flow cytometry. The LmCL response of neutrophils was reduced by laser irradiation at 60 minutes prior to the stimulation with opsonized zymosan and calcium ionophore. The attenuating effect of LLLT was larger in neutrophils of smokers than non-smokers, while the amount of produced ROS was larger in neutrophils of smokers. Expression of CD11b and CD16 on neutrophil surface was not affected by LLLT. The results indicate that attenuation of ROS production by neutrophils may play a role in the effects of LLLT in the treatment of inflammatory tissues. There is a possible utility of LLLT to improve wound healing in smokers.

Kolarova (Kolarova H et al. Effect of He Ne laser irradiation on phagocytic activity of leukocytes in vitro. Acta Universitatis Palackianae Olomucensis Facultanis Medicae. 1991.129(2): 127-132. reported that doses of 5–10 J/cm2 induced a significant increase in phagocytic activity of leukocytes in vitro.

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