Insights into molecular mechanisms of contact hypersensitivity gained fromgene knockout studies

Contact hypersensitivity (CHS), a dendritic-cell (DC)-dependent, T-cell-med iated skin immune response to reactive haptens, has been a subject of inten se research for many years. The molecular mechanisms underlying CHS are com plicated and are not fully understood. During the past few years, varieties of gene-targeted knockout mice have been used in the study of CHS. Such st udies have contributed significantly to our understanding of the mechanisms responsible for the initiation of CHS. This review focuses on insights int o molecular requirements for CHS gained from knockout studies.