Effects of low-level laser irradiation on human blood lymphocytes in vitro

Low-level laser irradiation (LLLI) has various effects on cultured human lymphocytes in vitro, but little is known about such effects in whole blood. This study investigated whether LLLI affected lymphocyte count in human whole blood in vitro. A total number of 130 blood samples were collected from apparently healthy adult patients through venipuncture into tubes containing EDTA. Each sample was divided into two equal aliquots to be used as a non-irradiated control sample and an irradiated sample. The irradiated aliquot was subjected to laser wavelengths of 405, 589, and 780 nm with different fluences of 36, 54, 72, and 90 J/cm 2 , at a fixed irradiance of 30 mW/cm 2 . A paired student t test was used to compare between non-irradiated and irradiated samples. The lymphocyte counts were measured using a computerized hematology analyzer and showed a significant ( P