Adhesion molecules on the plasma membrane of epidermal cells. III. Keratinocytes and Langerhans cells constitutively express the lymphocyte function-associated antigen 3.

It is now becoming clear that a collection of adhesion molecules is required on the surface of epidermal cells (EC) to establish the cell interactions that are necessary for skin immunologic reactions. In previous studies, we showed that human resting Langerhans cells (LC) express at least two members of the "integrins" family of adhesive molecules, as well as the intercellular adhesion molecule-1, which is a member of the immunoglobulin-related superfamily of molecules. This latter family includes another adhesive moiety, namely, the lymphocyte function-associated antigen-3 (LFA-3), which is the ligand for the T-lymphocyte-associated CD2 molecule, and has a broad tissue and organ distribution. In the present investigation the colloidal gold-immunoelectronmicroscopy immunostaining system and a quantitative analysis of the labeling provided decisive evidence for the weak but clear LFA-3 expression on virtually all keratinocytes (KC) and LC freshly isolated from normal human skin. Such constitutive expression of LFA-3 molecule on EC may be relevant for a number of functional interactions between LFA-3-positive EC and CD2-positive T lymphocytes within the cutaneous environment.