Cell Cycle Response to Low Power Laser Irradiation in Jurkat E6.1 T-lymphocyte Cell Line

Low-power laser irradiation (LPLI) effects on cell cycle progression in Jurkat E6.1 T-lymphocyte leukemia (JETL) cells were examined in vitro at 635nm (visible) and 780nm (near infrared) wavelengths. The cells were exposed to an energy density of 9.174 J/cm2, and then examined 24, 48 and 72 hours post-irradiation. Cell cycle analysis by flow cytometry at 24 hours post-irradiation revealed that the three phases (G0/G1, S and G2/M) of cultured JETL cells showed different percentages in LPLI (635nm and 780nm) and unirradiated cultures, but S phase cells were observed with significant increased percentages (55.6 and 55.7%, respectively) compared to controls (37.3%). At 48 hours, again cells at S phase were observed with much higher percentages than control cells (48.2 and 51.5% vs. 29.9%, respectively), and the difference was significant (P ? 0.05). At 72 hours, the S phase cells were also observed with much higher percentages than control cells (33.1 and 32.6% vs. 21.3%, respectively), and the difference was also significant (P ? 0.05). Keywords: Cell cycle, Jurkat E6.1 T-lymphocyte leukemia cell line, Low-power laser irradiation