Fibroblasts derived from patients with erythropoietic protoporphyria (EPP) are not sensitive to violet light and do not contain an excess of protoporphyrin (PP). Fibroblasts from both normal individuals and patients with EPP can take up very low concentrations of PP from culture medium. Cells grown in PP-containing medium showed a gradually increasing but limited uptake of PP and also an increased sensitivity to light. A sensitive scanning microfluorometric method has made it possible to demonstrate that the PP is mainly localized in the perinuclear granules. After exposure to violet light, cells photosensitized by PP in a culture medium showed increased membrane permeability as well as reduced reproductive capacity. Both of these photodamage effects can be repaired during postirradiation incubation in culture medium at 37 degrees C.

Cell Division↗

PubMed1977

The role of oxygen in the photodamaging effect on erythrocytes of some photoallergic and phototoxic compounds.

Red blood cells irradiated with longwave ultraviolet light in the presence of a number of photoallergic or phototoxic compounds showed a marked loss of K+ ions. This process was strongly restricted by anaerobic conditions. During irradiation, oxygen was consumed. Since pre-irradiated photosensitizers were not toxic to erythrocytes, it is concluded that during irradiation, oxidative processes take place in the erythrocyte. The concentrations of the investigated photoallergic compounds required to induce photohaemolysis, were several times higher than those required for the phototoxic compound protoporphyrin. These findings indicate that photoallergic compounds, like the photodynamic compounds, also have photo-oxidative capacities, but to a much lower degree.

Erythrocytes↗

PubMed1976

[The treatment of psoriasis with oral 8-methoxypsoralen and long-wave ultraviolet light].

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Humans↗

PubMed1975

Determination of protoporphyrin in plasma and suction-blister fluid from light-irradiated and non-irradiated skin in protoporphyria patients.

At various times of the year the protoporphyrin level in the plasma of 11 patients with erythropoietic protoporphyria was determined. In the winter as well as in the summer, when the patients received carotenoids, an area on one forearm of 10 patients was irradiated with artificial (xenon arc) light, after which suction blisters were made on both forearms. Protoporphyrin levels were determined in the plasma and in the blister fluid from both areas. Suction-blister fluid was considered representative of the interstitial fluid in the dermis. In the winter the protoporphyrin levels of the blister fluid from the irradiated area were significantly higher than in the fluid from the non-irradiated area. In the summer this difference was not significant. The possible implications of these findings are discussed.

Blister↗