Chemokines in the pathogenesis of lichenoid tissue reactions.

Clinical manifestations of lichenoid tissue reactions are heterogenous and include the cutaneous lupus erythematosus and lichen planus. Lichenoid tissue reactions are characterized by epidermal basal-cell damage and a variable subepithelial inflammatory infiltrate including cytotoxic T(H)1 cells and plasmacytoid dendritic cells. Here, we summarize the current knowledge of the role of chemokines in the pathophysiology of lichenoid tissue reactions and propose mechanisms by which recruitment and local activation of cytotoxic T(H)1 cells and plasmacytoid dendritic cells may result in initiation and amplification of lichen planus and cutaneous lupus erythematosus.