OBJECTIVETo investigate the significance of cytokine interleukin-12p40 (IL-12p40) and interferon-gamma (IFN-gamma) in tissues formation and development of human oral lichen planus (OLP).

METHODSThe tissues of 11 cases of normal oral epithelium and 43 cases of OLP were investigated for the expression of IL-12p40 and IFN-gamma proteins by using Envision two-step immunohistochemistry. The correlations between the expressions of these two cytokines, and their clinical and pathological significance in OLP were analyzed.

RESULTS1) IL-12p40 and IFN-gamma proteins were up-regulated in OLP comparing with that in normal oral mucosa and there was statistical significance between their difference (P < 0.05). 2) The percentage of positive IL-12p40 staining in OLP of IFN-gamma positive group was higher than IFN-gamma negative group and there was statistical significance between their difference (Chi2 = 5.828, P = 0.016). A positive correlation was found between IL-12p40 and IFN-gamma proteins in OLP (Spearman r = 0.357, P = 0.019). 3) The percentage of positive IL-12p40 staining in OLP with short course (< 6 months) was higher than that in OLP with long course (> 6 months; Chi2 = 7.935, P = 0.005), and a significant association was found between IFN-gamma over expression and the degeneration of base cells in OLP lesions (Chi2 = 9.070, P = 0.011).

CONCLUSIONThese results indicate that at the primary phase of OLP, IL-12 may drive the pathological destruction in OLP lesions by elevating IFN-gamma protein locally. IFN-gamma may play an important role for the pathological destruction in OLP lesions.