CD4+ T helper subsets are present in the sub epithelium and lamina propria in OLP lesions, and these CD4+ T cells can differentiate into different subsets, including Th1, Th2, Th9, and Th17 cells, depending on the cytokine environment, and may thus further amplify the immune response (Rengarajan et al., 2000; Vignali et al., 2008). The gene discussed is CD4; the disease is oral lichen planus.