Lysosomal hydrolases of the epidermis. 6. Changes in disease.

The activities of 14 acid hydrolases have been measured in normal and diseased human epidermis. Our findings were as follows: (i) Increased hydrolase activity was common in lesions; the clinically uninvolved skin of patients, however, invariably showed normal values. (2) The pattern of change was independent of the nature of the didease, the arylsulphatases and beta-glucosidase usually showing the greatest elevations. (3) The magnitude of the changes differed from disease to disease, being most marked in the lesions of psoriasis. (4) Ichthyosiform erythroderma was exceptional in showing elevated levels of the galactosidases and cathepsins B1 and D. We suggest that (with the exception of ichthyosiform erythroderma) the abnormalities which we have observed may be related to the proliferative rate of the epidermis.