Flavonoid And Low Level Long Wavelength Laser Irradiation Effects Seen In Human T Cells

The goal of present studies was to investigate human T cells death/survival/proliferation balance in response to low power far-red (FR) and near-infrared (NIR) laser irradiation doses and/or various concentrations of flavonoids Quercetin (QUE) or Epigallocatechin gallate (EGCG). Changes induced in mitochondrial reticulum state in correlation with apoptosis induction were additionally monitored. Peripheral blood derived lympocytes and human T leukemic Jurkat cells were cultured in standard conditions. QUE or EGCG were introduced in the culture media in various concentrations (1 - 150 μM) for various time periods (6 - 136 h). Therapeutic lasers with emission wavelengths in the range 600 - 900 nm were used to expose cells to single irradiation doses of 0.8-1.8 μJ/cell, with irradiation regimes of once per day, or every second day, realizing total irradiation doses of 1-15 μJ/cell. Using appropriate fluorophore-conjugated surface markers (AnnexinV-FITC for dying cells), mitochondrial (JC1 and MitoTracker dyes) and nuclear probes (7-AAD, Hoechst and PI as DNA stains), mitochondrial membrane depolarization / hyperpolarization related apoptosis induction, cell cycle blockade/progression, cell survival/death rates and cell death style choices were followed up by fluorescence/confocal microscopy and flow cytometry. The obtained data reveal significant, laser wavelength, dose, irradiation regime and cell state dependent photobiomodulation of flavonoid effects in human T cells.Partial financial support of the Romanian Ministry of Education and Research (grants CNCSIS 924/2006, CEEX 74/2006 and PN2-42139/2008) is gratefully acknowledged.