Objectives: 

Ultraviolet radiation (UVR) is a major exogenous factor which induce reactive oxygen species (ROS) synthesis by activation of the oxidative metabolism. Photo-oxidative stress is generates by the imbalance of UVR-induced ROS production and anti-oxidative mechanisms. The aim of our study was to appreciate the phagocytosis and ROS production in vitro, after blood's exposure to UVR.

Materials: 

Heparinized venous blood was collected from 15 porphyria cutanea tarda (PCT) patients. It was divided in three series of samples that were irradiated for 3, 5, and 15 min. The UVR exposure was performed in a dark room by means of an 80 W biological quartz lamp placed at a distance of 20 cm from the sample. In each series the pre-irradiation state served as control. The phagocytosis and ROS formation were evaluated by nitro-blue tetrazolium dye reduction test (NBT %). Reduction of NBT is performed by ROS produced in leukocytes during the phagocytosis process.

Results: 

In PCT patients, the NBT tests increased by 32.58%, 63.22% and 136% over the initial value correlated with the time of blood UVR exposure. That showed the activation of phagocytosis induced by UVR. Also, the results sustained the progressive cumulative effects of UVR on the oxidative metabolism and ROS formation in granulocytes. The results obtained in vitro were correlated with the clinical database which showed aggravation of the cutaneous lesions after solar exposure in PCT patients.

Conclusions: 

In vitro data showed an increase of ROS production in leukocytes in PCT patients after blood exposure to UVR. The obtained results substantiate that ROS production, at least partially, contributes to the detrimental effect of UVR on the skin of PCT patients.