APOPTOSIS AS A MECHANISM OF SKIN RENEWAL - LE(Y)-ANTIGEN EXPRESSION IS INVOLVED IN AN EARLY EVENT OF A CELLS COMMITMENT TO APOPTOSIS

Skin renewal is a typical example of the active participation of a cel l in its own death process. Cells arising from mitotic activity in the stratum germinativum of the epidermis continuously migrate upwards to the stratum corneum, where dead cells are eventually desquamated. Rec ent studies have suggested that apoptosis is involved in the dynamic p rocess of skin renewal. However, this still remains to be further eluc idated. In this paper, we investigated the involvement of apoptosis in the skin renewal process. Changes in the morphology of cells in diffe rent epidermal layers were compared with histochemical analyses of the extent of DNA fragmentation, as determined by nick end-labelling, and of the reactivities to a monoclonal antibody directed to Le(y)-antige n, difucosylated type 2 chain determinant, which has a close associati on with apoptosis, and to a monoclonal antibody directed to the prolif erating cell nuclear antigen. The results show that apoptosis proceeds concomitantly with cell movement in the epidermis. It seems likely th at commitment of a cell to death by apoptosis occurs in the epidermal tissue immediately after completion of cell proliferation, and that Le (y)-antigen expression may be involved in the entire apoptotic process including this early event.