RESUMO
<p><b>OBJECTIVE</b>To 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).</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>1) 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).</p><p><b>CONCLUSION</b>These 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.</p>