ERYTHROPOIETIC PROTOPORPHYRIA: PHOTODYNAMIC TRANSFER OF PROTOPORPHYRIN FROM INTACT ERYTHROCYTES TO OTHER CELLS

Atle Brun, André Western, Zvi Malik, Sverre Sandberg

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Erythrocytes in patients with erythropoietic protoporphyria (EPP) contain large amounts of protoporphyrin and are regarded as the main source of protoporphyrin in this disease. Cells in the skin of EPP patients accumulate protoporphyrin released from the erythrocytes and upon sun exposure endothelial cells are photodamaged. In the present study a light‐induced transfer of protoporphyrin directly from EPP erythrocytes to cultured cells is demonstrated. Erythrocytes were layered upon cultured cells and irradiated. The nearness of erythrocyte and cultured cell membranes potentiated the transfer of protoporphyrin between these cells. This transfer was rapid and preceded the release of protoporphyrin to proteins in the medium. Further irradiation of the protoporphyrin‐enriched cultured cells, after removal of the erythrocytes, caused severe photodamage to the cells and survival was dependent on both the amount of protoporphyrin transferred and on the light fluence. Clinical observations and the results of this study indicate that light energy may be involved in two steps in the pathophysiology of EPP: (A) light‐induced release of protoporphyrin from erythrocytes to endothelial cells and (B) photodynamic damage to protoporphyrin‐enriched endothelial cells.

Original languageEnglish
Pages (from-to)573-577
Number of pages5
JournalPhotochemistry and Photobiology
Volume51
Issue number5
DOIs
StatePublished - May 1990

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