| Abstract: | J Oral Pathol Med (2011) 40 : 525–532 Background: Oral lichen planus (OLP) is a T‐cell‐mediated chronic autoimmune disease whose precise etiology is unknown. The recently identified costimulatory programmed death‐1 (PD‐1) molecule and its ligands, PD‐L1 and PD‐L2, have been identified as CD28‐B7 family molecules and constitute a regulatory pathway of potential therapeutic use in immune‐mediated diseases. Methods: We examined the expression of two ligands of PD‐1 at both the protein and gene level in the focal mucosa and peripheral blood of OLP patients using immunohistochemistry and real‐time PCR. Next, we used the PD‐L2.Ig fusion protein and observed its effects on T cells, which were co‐cultured with IFN‐γ‐treated keratinocytes (KCs) in the presence of PHA. Results: We found that the expression of PD‐L2 at both the gene and protein level was statistically different in peripheral blood and local lesion tissue of patients with OLP compared to the normal controls. The proliferation ability of T cells and the expression level of IFN‐γ in the supernatant of the above co‐culture model were significantly augmented (P < 0.05). PD‐L2.Ig fusion protein significantly aggravated the apoptosis of T cells, inhibited the proliferation of T cells and decreased the release levels of IL‐2 and IFN‐γ in the model (P < 0.05). Conclusion: These data show that the increased expression of PD‐L2, as a costimulatory molecule, may have an important modulatory function on the local immune responses of OLP in vivo. |
