Localization of transforming growth factor-alpha RNA and protein in the skin of psoriatic patients receiving therapy.

Fourteen patients with chronic plaque psoriasis requiring in-patient therapy were treated with a variety of antipsoriatic agents. All had four skin biopsies taken: two prior to therapy, one from a psoriatic plaque and one from adjacent clinically normal skin, and two further biopsies, one 2-3 weeks after starting therapy, and one at clinical clearance, taken from an area where there was previously a psoriatic plaque. In addition, three biopsies were taken from clinically normal skin of non-psoriatics. Transforming growth factor-alpha (TGF-alpha) RNA and protein distributions were estimated in these biopsies, using in situ hybridization with a cRNA TGF-alpha probe, and an antibody to TGF-alpha polypeptide. Prior to therapy, grain counts showed elevated levels of TGF-alpha RNA in the subcorneal layers of the epidermis. These levels decreased during clearance of the psoriasis. In one patient whose plaques did not clear, there was no decrease of TGF-alpha mRNA. Antibody studies showed the presence of TGF-alpha polypeptide in the epidermis prior to therapy, with a relative concentration of immunoprotein in the upper epidermal layers, compared with a more uniform distribution of immunoprotein after treatment, and in uninvolved skin of the same psoriatic patient. These studies extend our knowledge of the relationship between TGF-alpha and psoriatic skin.