Effect of soluble complement receptor type 1 on porphyrin-induced phototoxicity in guinea pigs.

The effect of recombinant human soluble complement receptor type 1 (sCR1) on the porphyrin-mediated phototoxic reaction was evaluated in guinea pigs. Phototoxicity was induced in the animals by intraperitoneal injection of hematoporphyrin derivative (HpD), followed by irradiation at a wavelength range of 320-450 nm. sCR1 administration decreased CH50 titers in a dose-dependent fashion, while it only moderately suppressed HpD/radiation-induced ear swelling at a high dose. These findings suggest that phototoxic dermatological changes in cutaneous porphyrias are not solely due to complement activation.