In vitro studies suggested that exogenous IL-23 could increase the percentage of Th17 cells and IL-17 production by CD4+ T cells of reticular OLP patients, and enhance the expression of cytokines, such as IL-8 and TNF-α, but not of IL-6 in human oral keratinocytes (HOKs) [73]. This evidence concerns the gene IL17A and oral lichen planus.