Up-regulation of intercellular adhesion molecule-1 (ICAM-1) and cytokines associated with Th 1 immune response, such as interferon (IFN)-gamma, tumour necrosis factor (TNF)- alpha, interleukin (IL)-1 alpha, IL-6 and IL-8, may also play a role in the pathogenesis of lichen planus (Chen et al., 2007). This evidence concerns the gene IFNG and lichen planus.