Effects of high and low doses of He:Ne laser irradiation on human lymphocytes in vitro

ABSTRACT

Low level laser irradiation [LLLI] can cause cell proliferation, differentiation, or death; however, the cellular mechanisms of these effects of LLLI, at high or low fluences. The exact mechanism of action of the laser radiation with living cells is not yet understood. Since HeNe has been shown to increase mitochondrial respiration it is relevant to study the effect of different high and low laser fluencies on mitochondrial proteins involved in apoptosis. The aim of this work was to study safety aspects of the effect of different high and low HeNe laser fluencies on mitochondrial proteins involved in apoptosis. Expression of Bax mRNA and Bcl-2 lymphocytes together with mitotic index and viability percentage together with the frequency of micronuclei were evaluated after exposing cells with a 10 mW He-Ne laser [wavelength 632.8 nm] at energy densities of 1, 2.5, 5, 10, 35 and 60 J/cm[2]. At low level HeNe laser irradiation induced a significant increase in Bcl-2 and an increase in viable cell percentage. However, at moderate dose there was an increase in Bax mRNA expression and decrease in viability percentage at doses ranging from 15 -60 J /cm[2]. Bcl-2 family proteins are stimulated by HeNe laser irradiation, which is safe at doses below 10 J /cm[2] and comparatively very safe, when compared with low doses of ionizing radiation