Two tris urea mercaptoethanol extractable polypeptides found uniquely in scales of patients with psoriasis.

This study was designed to chemically characterize the principal structural proteins of psoriatic scales. Cornified cells were obtained from 40 patients with psoriasis, 21 patients with other scaly diseases, and 13 normal individuals. Cells were washed with Tris-HCl buffer and incubated in 8 M urea containing 2-mercaptoethanol (pH 9.0) at 30 degrees C for 7 hr. Extracted proteins were subjected to SDS polyacrylamide gel electrophoresis and protein patterns from normal and diseased scales were compared. The 67,000 dalton constituent of normal cornified cells could not be identified in protein from psoriatic scale and instead, a pair of polypeptides of approximately 54,000 and 57,000 daltons appeared. These extra bands were not found in protein extractions from other skin diseases, uninvolved skin of psoriasis patients, or normal skin. In order to analyze further normal and psoriatic scale proteins, the immunoreaction of rabbit antisera to human 67,000 dalton polypeptide with extracted psoriasis protein and with frozen biopsy sections, was studied using immunoprecipitation tests and indirect immunofluorescence microscopy. Both techniques demonstrated the existence of the 67,000 dalton protein in psoriasis, but as a minor component. These results indicate that additional unique urea mercaptoethanol soluble proteins are formed in psoriatic lesions, and this unusual protein synthesis may reflect the morphological changes in this disease.