Quantification of alkaline phosphatase in lesions and uninvolved skin of psoriatic patients.

: Alkaline phosphatase (ALP) has been quantified in psoriatic skin for the first time. The levels of both the soluble and the particulate forms of this enzyme were grossly elevated in psoriatic lesions; by contrast, levels in the clinically uninvolved skin of the patient were normal. The changes in the lesion cannot be explained solely in terms of vasodilatation, since UVR-induced erythema was accompanied only by a modest increase in soluble ALP activity.