Induction of Thy-1 antigen on murine keratinocytes.

In normal murine epidermis Thy-1 antigen is known to be strongly expressed on a dendritic population of bone marrow derived cells lacking Ia antigens and faintly on keratinocytes. We now report on the induction of pronounced expression of Thy-1 antigen on keratinocytes by immunological stimuli as well as by chemical irritation and wounding. In contrast the induction of Ia antigens on keratinocytes is more restricted. It has been suggested that the dendritic Thy-1+ cells can suppress an immune response initiated by Ia antigen expressing Langerhans cells. The balance within epidermis between up- and down-regulation of immune reactions, may be even more complex if also keratinocytes expressing Thy-1 and/or Ia antigens should prove to participate.