Adhesion molecule expression by epidermal Langerhans cells and lymph node dendritic cells: a comparison

The migration of epidermal Langerhans cells (LC) and their transport of antigen from the skin to draining lymph nodes are of considerable importance in the induction of cutaneous immune responses, including contact sensitization. While in transit to the lymph nodes, LC are subject to a number of phenotypic changes required for their movement from the skin and acquisition of the capacity for antigen presentation. Among these are alterations in the expression of adhesion molecules that regulate interactions with the surrounding tissue matrix and with T lymphocytes. In the study described here, we investigated, using a combination of immunocytochemistry and flow cytometry, the expression by LC, and the lymph node dendritic cells into which they mature, of the three adhesion molecules, E-cadherin, intercellular adhesion molecule-1 (ICAM-1) and the membrane glycoprotein CD44. The migration of LC was associated with a marked reduction in the expression of E-cadherin, but a parallel upregulation of ICAM-1. No change in the expression of CD44 was detectable. The significance of these changes and their relevance for the functional maturation of LC are discussed.