Preferential replication of Sézary cells in the epidermis.

Skin biopsies from three patients with Sézary Syndrome have been labeled in vitro with H-3Thymidine. Labeled cells have been counted in semithin Epon embedded sections and characterized by electron microscopic autoradiography. The ratio of labeled Sézary cells to total lymphocytes was two to four times higher in the epidermis than in the dermis. It is concluded that Sézary cells replicate in the skin and that epidermal cells seem to possess new blastogenic properties in Sézary Syndrome.