T-CELL-MEDIATED TERMINAL MATURATION OF DENDRITIC CELLS, A CRITICAL TRANSITION INTO FULLY POTENT ANTIGEN-PRESENTING CELLS

Dendritic cells (DC) are a special subset of leukocytes characterized by their potent ability to activate immunologically naive T cells. We established a series of long-term DC lines, termed <<XS lines>>, from the epidermis of newborn mouse skin. These lines retain many important features of resident DC in epidermis, i.e., Langerhans cells (LC), in cluding surface phenotype, antigen (Ag) presenting capacity, and cytok ine and cytokine receptor profiles. Working with XS lines, we have obs erved recently that DC undergo rapid and profound changes during Ag pr esentation. Specifically, upon Ag-specific interaction with T cell clo nes, XS52 cells: a) begin to secrete several cytokines (IL-1 beta, IL- 6, and TNF(alpha), b) lose the expression of CSF-1 receptor and prolif erative responsiveness to CSF-1, c) elevate the expression of B7-2 (CD 86), and d) lose the phagocytotic and adhesive capacities. We propose that these changes represent <<T cell-mediated terminal maturation>> o f DC, a critical transition into a fully professional Ag presenting ce ll.