Evaluation of interleukin-6 levels in saliva of patients with oral lichen planus

Oral lichen planus (OLP) is a chronic mucocutaneous inflammatory disorder with an unknown etiology. Although a considerable body of evidence suggests that immunologic factors are involved in the etiology of OLP, the involvement of cytokines in the pathogenesis of the disease is not fully understood yet. The aim of the present study was to assess interleukin-6 (IL-6) levels as a proinflammatory cytokine in the saliva of OLP patients compared to healthy controls.

This case-control study was conducted on 30 OLP patients (12 males and 18 females)  and 30 healthy control subjects, selected from individuals who were referred to the Department of Oral and Maxillofacial Diseases in Faculty of Dentistry, Babol University of Medical Sciences. Samples of unstimulated saliva were collected. Salivary IL-6 levels were measured using an ELISA kit and compared between OLP patients and healthy controls. The collected data were analyzed by Chi-square, independent t-test, and receiver operating characteristic (ROC) curve using SPSS 18 Sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) ​​were calculated. A value of p<0.05 was considered significant.

Mean salivary IL-6 values in OLP patients and healthy controls were 24.68±9.90 ng/L and 13.76±9.27 ng/L, respectively. The difference was statistically significant (P<0.001). The mean IL-6 values in reticular and erosive forms of OLP clinically were 24.35±9.26 ng/L and 24.91±10.64 ng/L, respectively. This difference was not statistically significant (P=0.87).

Higher levels of IL-6 in saliva of OLP patients compared with healthy controls support the role of IL-6 in the pathogenesis of the disease.