Relative Variation to Received Dose of Some Erythrocytic and Leukocytic Indices of Human Blood as a Result of Low-Level Laser Radiation: An in Vitro Study

Objective: This study investigated the in vitro effects of low-level laser radiation (LLLR) on selected rheologic constants of the human blood. The variations of CBC parameters to the received dose were determined, as well as of blood viscosity (an erythrocyte aggregation index), as a research method for some structural alteration of blood proteins. This was also confirmed by the electrophoretic study of plasma proteins from the irradiated blood. Methods: Fresh blood samples (whole blood) from 16 adult regular blood donors were irradiated with a He-Ne laser (λ = 632.8 nm; power output= 6 mW; mean irradiance on blood samples ≈ 180 mW•cm^-2; beam spot diameter ≈ 2 mm), operating in continuous wave. Doses ranged between 0 (control sample) and 9.346 J•cm^-3. EDTA (for CBC and viscosity measurements) or citrate (for electrophoresis) anticoagulant was used. Measurements were performed before (control samples) and after irradiation. In most of the cases, the measurements were made immediately after irradiation. In some cases, the measurements were made after 24 or 48 h after irradiation, respectively, to conclude whether the modifications caused from irradiation occur in time, or immediately after irradiation. Results: Following irradiation, marked variations of some erythrocyte and leukocyte indices and changes of the erythrocyte aggregation (viscosity), as a function of received dose, were observed. Significant differences between control and irradiated blood samples were found for the following rheologic factors: RBC (in 22.2% of cases); HGB (26.8%); HCT (82.4%); MONO and GRAN (36.7%); viscosity (82.5%). From the plasma proteins: albumin (22.2%); alpha 1 globulin and gamma globulin (18.5%); fibrinogen (70.4%). In most of the cases, remarkable effects (maxima) were noticed around 1.2 J•cm^-3 dose value. We consider this dose value as optimal, one that can lead to beneficial effects. The cell membrane integrity was not affected from irradiation, for doses between 0 and 9.346 J•cm^-3, and will probably not even be affected at higher doses (see MCV and MCHC behavior). Conclusions: The effect of LLLR on red blood cells confirms the nonresonant mechanism of this biostimulating effect, by the changes occurring in the cell membrane (in our case, blood cells), by revitalizing of red blood cell functional capacities and by several biochemical effects at the membrane's level. These are to be studied thoroughly in future studies. The physical-biochemical and biological effects caused by LLLR on blood can influence the physical-chemical parameters needed for the long-term storage of blood products. These effects can also lead to a quicker revitalization of the erythrocyte membrane (which was subjected to the action of some physical and biochemical factors during the preservation process), to perform its oxyphoric function in transfusion procedures.