Role of distinct CD 4 + T helper subset in pathogenesis of oral lichen planus

Oral lichen planus ( OLP ) is one of the most common chronic inflammatory oral mucosal diseases with T‐cell‐mediated immune pathogenesis. In subepithelial and lamina propria of OLP local lesions, the presence of CD 4 + T helper ( CD 4 + Th) cells appeared as the major lymphocytes. These CD 4 + T lymphocytes can differentiate into distinct Th cell types such as Th1, Th2, Treg, Th17, Th22, Th9, and Tfh within the context of certain cytokines environment. Growing evidence indicated that Th1/Th2 imbalance may greatly participate into the cytokine network of OLP immunopathology. In addition, Th1/Th2 imbalance can be regulated by the Treg subset and also greatly influenced by the emerging novel CD 4 + Th subset Th17. Furthermore, the presence of novel subsets Th22, Th9 and Tfh in OLP patients is yet to be clarified. All these Th subsets and their specific cytokines may play a critical role in determining the character, extent and duration of immune responses in OLP pathogenesis. Therefore, we review the roles of distinct CD 4 + Th subsets and their signature cytokines in determining disease severity and susceptibility of OLP and also reveal the novel therapeutic strategies based on T lymphocytes subsets in OLP treatment.