Monoclonal antibodies for epidermal population analysis.

Three keratin antibodies (RKSE 60, Clone 77, and a rabbit polyclonal) and 2 vimentin antibodies (Vim ab and a rabbit polyclonal) were investigated using frozen sections of normal and psoriatic skin. Of these, the monoclonals RKSE 60 and Vim ab were selected for quantitative population analysis of healthy epidermis, psoriatic uninvolved epidermis, and psoriatic lesions. Suspensions of isolated cells were prepared from biopsy specimens by trypsinization, and stained with RKSE 60 or Vim ab using an indirect immunofluorescence assay. Our results showed an increase in the germinative fraction from the normal value of 30% to almost 50% in the psoriatic lesion; in absolute terms this corresponds to a 6-fold increase in the size of the germinative compartment. More interesting, the germinative psoriatic uninvolved epidermis (38%) was also significantly higher than normal. The percentage of vimentin-positive cells (Langerhans cells and melanocytes) was nearly double that of normal in both the lesion and the uninvolved psoriatic epidermis. We conclude that, in contrast to statements frequently encountered in the literature, the "uninvolved" skin of the patient is morphologically and functionally different from that of the healthy individual.