CONTINUOUS WAVE VISIBLE RED (633 nm) LASER ENERGY ENHANCES THE DEGRANULATION OF MAST CELLS: A POSSIBLE PHOTOMEDIATED WOUND HEALING MECHANISM EXAMINED IN VIVO

Abstract

The mast cell in an interesting repostory of a number of pro- and anti-inflammatory mediators, and plays an important role in the inflammatory stage of the wound healing process, and in allergic reactions. The present study was designed to elicit the effect of visible light radiation at 632.8 nm (visible red) on mast cells in vivo using light and transmission electron microscopy. The tongue of the Swiss mouse is rich in mast cells (MCs). Tongues of animals in two experimental groups were irradiated using a HeNe laser (15 mW & 4 mW, 2.4 J/cm2,for both output powers, λ = 632.8 nm), and a third set of unirradiated animals served as the control. The two output powers were used, with the irradiation time adjusted to produce the same energy density. The possible nonselective degranulation of LLLT-irradiated mast cells was examined quantitatively and morphometrically using optic and electron microscopy. By means of radioimmunoassay, the histamine content of pulverized tongue was evaluated, and the histamine levels in both experimental and control tissue were compared. The irradiated tongue tissue showed a significantly higher histamine level compared with the control. In addition, the level of histamine in the interstitial cellular medium and the degree of other histological changes such as vasodilation was significantly higher following a single irradiation with the HeNe laser at the above settings. The observations from this study may serve as a further indication of the bioactivative effect of low reactive level laser therapy on mast cells, which are an important component of the wound healing process and inflammation control.