Expression of c-myc protein in skin and synovium in psoriasis and psoriatic arthritis.

Monoclonal antibody against c-myc protein was used in the avidin-biotin-peroxidase complex procedure to examine frozen sections of psoriatic and normal skin and psoriatic synovium for the presence of c-myc protein. A significantly greater percentage (88%) of epithelial cells from psoriatic skin lesions stained for c-myc than uninvolved skin (62%) from both psoriatics and normals (p less than 0.001). The intensity of the stain appeared weaker in normal skin specimens. Greater than 95% of psoriatic hyperplastic synovial lining cells stained strongly for c-myc. In all cases, the c-myc staining was confined to the nuclei with no evidence of cytoplasmic staining.