Significant statistical differences were demonstrated between the reaction of normal control skin and apparently unaffected skin from psoriatic patients following the application of a standard insult. A greater thickening in psoriatic epidermis compared with normal controls was demonstrated and there was also a greater liberation of hydrolytic enzymes. It is postulated that these findings reflect an inherent instability of lysosomal enzymes in psoriatic epidermis and it is possible that this defect may be an important factor in the genesis of this disorder.
Reid J, Jarrett A. Enzymatic and Histological Effects of a Standard StimulusTo the Skin of Normals and the Clinically Normal Skin of Psoriatics. Arch Dermatol. 1967;95(6):632-641. doi:10.1001/archderm.1967.01600360078013