A. IFTIME*, E. RADU**, EVA KATONA*

*Department of Biophysics, Medical Faculty, “Carol Davila” University of Medicine and Pharmaceutics, Bucharest, Romania
**Department of Molecular and Cellular Medicine, Medical Faculty, “Carol Davila” University of Medicine and Pharmaceutics, Bucharest, Romania

Abstract. We investigated the effects of low power 680 nm far-red (FR) and 830 nm near-infrared (NIR) laser light on control and energy restricted human peripheral blood mononuclear cells (PBMC) viability, and apoptosis rate in presence and absence of growth factors. Data obtained both by microscopy and by flow cytometry demonstrated significant changes in the explored parameters. Energy restriction induced by blockade of oxidative phosphorylation with various concentrations of cyanide caused cell microenvironment, toxicant concentration, and intoxication duration dependent viability decrease, and apoptosis induction. Multiple NIR laser irradiation of the whole PBMC population in absence of growth factors offers slight transient protection against viability decrease during mid intoxication periods, but mildly enhances apoptosis induction in intoxicated cells after longer periods of exposure. In same conditions, viability and apoptosis induction in control cells are not significantly affected. However when the Ly subpopulation is irradiated separately alone, NIR laser light drastically reduces viability of the whole PBMC population in control samples, while still offers transient protection to cyanide intoxicated cells. Low dose FR irradiation does not significantly affect the viability of control, mildly or highly intoxicated human PBMC in absence of growth factors, but drastically enhances toxicity of mid cyanide concentrations. In presence of growth factors, either of the irradiation regimes are applied, neither NIR nor FR irradiation has any effect on control human PBMCs viability. In same conditions NIR irradiation of the whole PBMC population induces short term viability increase and long term protection against cyanide induced viability decrease. NIR irradiation of the Ly subpopulation only offers mild transient protection against cyanide toxicity caused viability decrease of human PBMC, while FR irradiation in presence of the same cyanide concentration enhances this viability decrease. Applying the same irradiation regime FR irradiation can offer mild transient protection against cyanide toxicity at much lower cyanide concentrations.

Key words: low level laser therapy (LLLT), cyanide-intoxication, photobiomodulation, apoptosis induction.

Corresponding author’s e-mail: ad_if@yahoo.co.uk

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