Salivary Interferon Gamma and Interleukin-4 Levels in Patients Suffering from Oral Lichen Planus

Oral lichen planus (OLP) is a chronic inflammatory disease. Immunological factor may act as etiological factor. The cellular immune cells such as T cells are important in pathogenesis. Interferon gamma (IFN-γ) and interleukin 4 (IL-4) are secreted by T-helper 1 (Th1) and Th2, respectively. The aim of this study was to investigate the correlation between salivary levels of IFN-γ and IL-4 with OLP. This case control study included sixty three Iranian OLP patients who were selected from the Department of Oral Medicine of Ahvaz Jundishapur University of Medical Sciences from January to July 2013. An equal number of healthy volunteers were also selected as a control group. The OLP patients were then divided into two following sub-groups: reticular (n=30) and erythematous/ulcerative (n=33). All patients had no systemic disease and received no medication. IFN-γ and IL-4 levels in whole unstimulated saliva (WUS) were measured using the enzyme-linked immunosorbent assay (ELISA) test. Data analysis was done using t test, ANOVA, least significant difference (LSD) test, and the Kruskal-Wallis test. Reticular OLP patients showed higher salivary IFN-γ (7.74 ± 0.09 pg/ml) and IL-4 (3.876 ± 0.05 pg/ml) levels compared with the control group, indicating that difference was significant. Salivary IFN-γ/IL-4 ratio significantly increased compared with control group (P=0.042). Salivary IFN-γ and IL-4 levels between sub-groups (reticular and erythematous/ulcerative) were not significantly different (2.6 ± 0.06 and 2.3 ± 0.05, respectively, P<0.05). Salivary IFN-γ and IL-4 levels were increased in OLP patients. An increase of salivary IFN-γ/IL-4 ratio in OLP patients showed that Th1 might have a dominant role in the OLP pathogenesis.