Photohemolysis. The Comparative Behavior of Erythrocytes from Patients with Different Types of Porphyria 1

Abstract

Porphyrins have long been recognized as being involved in light-induced tissue damage. Fischer (1) was probably the first to describe their role in photohemolysis. Other early studies were carried out by Günther (2) and by Kammerer and Weisbecker (3) who varied several parameters as well as comparing the effectiveness of more than one porphyrin. Later Cook and Blum (4) found that the photohemolysis of normal red cells required oxygen and suggested that the hemolysis was attributable to their protoporphyrin content. Interest in this phenomenon was revived when Harber et al. (5) noted the unusual susceptibility to photohemolysis of erythrocytes from patients with erythropoietic protoporphyria. This is a recently recognized disease of porphyrin metabolism in which there is an abnormal skin sensitivity to sunlight and greatly increased levels of protoporphyrin in erythrocytes and feces. Subsequent investigations led Fleischer et al. (6) to conclude that the photohemolysis of these protoporphyrin-containing cells involves membrane damage, then increased permeability, and finally colloid osmotic lysis.

The occurrence of skin symptoms in certain other types of porphyria, as well as a high erythrocyte porphyrin concentration in one, posed the question of possible photohemolysis in these other diseases of porphyrin metabolism. Therefore, the present investigation was undertaken as a possible aid in understanding the photohemolytic process. Compared are the behavior toward irradiation of normal erythrocytes and those from patients with four different types of porphyria that are characterized by cutaneous manifestations: erythropoietic protoporphyria (EPP), congenital erythropoietic porphyria (CEP), South African porphyria (porphyria variegata), and porphyria cutanea tarda. Also compared are the photohemolytic properties of uro-, copro-, and protoporphyrins when added to erythrocytes.

Methods. Erythrocytes from citrated or heparinized human blood were washed three times with 0.9% sodium chloride, then routinely suspended in Hanks' solution at a dilution of 1:2000.