Abstract
Objective: Visible light irradiations at doses of 5 and 12 J/cm2 were applied to carp buffy coat leukocytes. Materials and Methods: The leukocytes response was measured by a chemiluminescence (CL) assay as basal (spontaneous) bCL and Ca ionophore-induced stimulated CL (StCL). Results: The irradiation caused a significant decrease in bCL in six out of 14 fish (susceptible fish) and rendered eight out of 14 fish unsusceptible. An inhibitory effect of light intensity dependence was more pronounced at 12 J/cm2 . Furthermore, this inhibitory effect of irradiation on bCL was found in fish which displayed higher (433 ± 90 cpm/mL) pre-irradiation bCL, compared to unsusceptible subjects (88 ± 30 cpm/mL, p < 0.05). Similar differences in the intensity of preirradiation StCL were found between these fish groups (13,053 ± 5086 as compared to 1077 ± 294, p = 0.03). Moreover, the time-to-peak of StCL was significantly shorter in susceptible fish, indicating their hyper-reactivity. Conclusion: These data show the inhibitory effect of visible light irradiation on blood leukocyte CL response in fish. These results suggest the prevention of host hyper-response which may occur under natural conditions of fish life. An Electron Paramagnetic Resonance (EPR) study of illuminated carp blood cells reveals the formation of Ascorbate free radicals (AFR) that may explain the decrease in reactive oxygen species (ROS) concentration following irradiation.
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