FoxP3⁺CD4⁺, IFN-γ⁺CD4⁺, and IFN-γ⁺CD8⁺ cell levels in erosive and non-erosive types of oral lichen planus patients

Background/purpose: Oral lichen planus (OLP) is a localized autoimmune oral mucosal disease. This study evaluated whether different types of OLP patients including erosive OLP (EOLP), major EOLP, minor EOLP, and non-erosive OLP (NEOLP) patients had significantly higher percentages of FoxP3⁺CD4⁺ or IFN-γ⁺CD4⁺ cells in total CD4⁺ cells, and of IFN-γ⁺CD8⁺ cells in total CD8⁺ cells than healthy control subjects and whether the patient's age had significant influences on these cell percentages in OLP patients. Materials and methods: Flow cytometry was used to count the FoxP3⁺CD4⁺, IFN-γ⁺CD4⁺, or IFN-γ⁺CD8⁺ cell levels in 183 OLP patients (67 major EOLP, 81 minor EOLP, and 35 NEOLP patients) and 20 healthy control subjects. Results: Major EOLP patients had a significantly higher FoxP3⁺CD4⁺ cell percentage than health control subjects (P = 0.049) or minor EOLP patients (P = 0.008). Major EOLP patients had a significantly higher IFN-γ⁺CD4⁺ or IFN-γ⁺CD8⁺ cell percentage than healthy control subjects, NEOLP patients, or minor EOLP patients (all P-values < 0.01). In addition, both 61–80 year and 41–60 year OLP patients had significantly higher IFN-γ⁺CD8⁺ cell percentages than healthy control subjects or 20–40 year OLP patients (all P-values < 0.005). Conclusion: Major EOLP patients tend to have significantly higher percentages of FoxP3⁺CD4⁺, IFN-γ⁺CD4⁺, and IFN-γ⁺CD8⁺ cells than healthy control subjects, NEOLP patients or minor EOLP patients, suggesting that FoxP3⁺CD4⁺ Treg cells are increased to modulate OLP disease activity. Increased number of IFN-γ-producing activated T cell may be involved in oral epithelial cell destruction in OLP patients.