The effect of PUVA therapy on glycoprotein biosynthesis in uninvolved psoriatic epidermis

Protein and N-linked glycoprotein biosynthesis was studied in the uninvolved epidermis of patients with psoriasis by the incorporation of radiolabelled leucine and mannose prior to and during PUVA treatment. Analysis of the polyacrylamide gel electrophoresis (PAGE) patterns of the 3[H]-labelled proteins and glycoproteins showed that the major changes in untreated uninvolved psoriatic epidermis compared to normal epidermis were: (a) a shift towards the synthesis of low-molecular-weight glycoproteins; (b) the absence of a 48-kDa peak labelled with mannose; (c) the appearance of 3[H]-mannose-labelled peaks at 40-36 kDa. PUVA treatment gradually changed the PAGE profile back more towards that expected for normal epidermis, with the reintroduction of a 52-48-kDa glycoprotein and reduction of the peaks in the 40-34-kDa region. This effect was dependent on uninterrupted treatment. The PUVA-treated PAGE profiles were compared to those expected in skin tumours (i.e. increased 3[H]-mannose-labelled peaks at 95 and 40-34 kDa with an absence of 62-kDa peaks). It appeared that these criteria were not seen generally as a result of PUVA treatment. However, the results indicate that tumour development may be possible if a patient responds to PUVA treatment by showing an increased peak at 95 and 40-34 kDa in association with a loss of an 3[H]-mannose-labelled peak at 62 kDa.