Increase in reactive oxygen species production and phagocytic activity of polymorphonuclear neutrophils stimulated by preirradiated hematoporphyrin derivative solution

We have studied the influence of preirradiated by visible light hematoporphyrin derivative(HpD) solution in PBS on the production of reactive oxygen species (ROS) and phagocytosis of latex particles by rat peritoneal polymorphonuclear neutrophils (PMN), and also on the delayed type hypersensitivity reaction (DTH) to sheep red blood cells in mice. The release of ROS and phagocytic activity were observed by means of registration of the luminol-enhanced chemiluminescence (ChL) in the absence (spontaneous ChL) and in the presence of latex particles. Non-irradiated HpD did not influence neither spontaneous ChL, response, nor latex-activated. HpD (0.3 mu g/ml) preirradiated by 135 J/m(2) did not affect spontaneous, but increased latex-activated ChL response by 20%. This fact indicates an increase in PMN phagocytic activity under the treatment with preirradiated HpD. Increase in preirradiation fluence up to 8.1 kJ/m(2) resulted in significant enhancement of spontaneous ChL (223%) and inhibition of latex-activated ChL, response (84%) of PMN. Results of spectroscopic analysis showed negligible decrease in HpD Soret band after preirradiation of HpD by the highest fluences used in this study. We could not detect any significant photoproduct formation by differential absorption spectroscopy. Earlier, we have proposed the photoinduced aggregation as one of the possible mechanisms of photodegradation of aqueous porphyrin solutions. In all probability, the increase in ROS production by PMN, treated with preirradiated HpD can be attributed to the phagocytosis of aggregates formed. It is possible that ROS can influence directly the DTH-effector cells leading to the observed decrease in DTH reaction level.