Activity of aryl hydrocarbon hydroxylase in psoriatic skin.

The activity of aryl hydrocarbon hydroxylase (A.H.H.), a microsomal mono-oxygenase, was reduced in epidermis from both the psoriatic lesions and clinically normal lesion-free skin from psoriatic patients. Induction of epidermal A.H.H. activity by benzanthracene was also significantly less than normal in both psoriatic lesions and in clinically normal skin from patients with psoriasis. The enzyme defect may be related to the primary genetic abnormality of the disease.