The Thy-1 epidermal cell: perspective and prospective.

Recently a class of cells distinguished by the presence of the cell-surface protein, Thy-I, has been discovered in the epidermis. These cells constitute a heterogeneous population such that they may be dendritic or round, and may be derived from both mesenchymal and ectodermal tissue. Phenotypically, cells with the following characteristics have been observed: Thy-I +, Vim+; Thy-I+, Vim-; Thy-I+, Ker+; Thy-I+, Ker-; Thy-I+, asialo GMI+; Thy-I+, asialo GMI-. Thy-I+ epidermal cells do not appear to be T or B lymphocytes, macrophage/monocytes or melanocytes. The Thy-I+ epidermal cell can be studied in in vivo and in vitro systems. It would appear that skin as well as the immune system contain Thy-I+ and Ia+ cells. Such cells may be prerequisite for both systems to carry out their primary defense functions.