Regulation of human leukocyte antigen expression in human conjunctival epithelium

Purpose. To demonstrate that interferon-γ (IFN-γ) is the key cytokine responsible for the upregulation of HLA-DR antigen in conjunctival epithelial cells of Sjogren syndrome (SS) patients. Methods. Flow cytometry of conjunctival epithelial cells from SS and non-SS dry eye patients was performed for the quantification of HLA-DR surface expression. With a conjunctival epithelial cell line (ChWK), HLA-DR regulation by various cytokines was evaluated, and confocal immunocytochemical and western blot analyses were performed to evaluate the activation of nuclear factor-kappa B (NF-κB) and signal transducers and activators of transcription 1 and 3 (STAT1 and STAT3, respectively). Results. HLA-DR expression was upregulated in conjunctival epithelial cells of SS patients but not in non-SS dry eye patient or healthy control subject. IFN-γ was the only cytokine that effectively upregulated HLA-DR expression in ChWK, which was synergistically enhanced by tumor necrosis factor-α (TNF-α). IFN-γ induced the nuclear translocation of NF-κB, but did not activate STAT1 or STAT3 in ChWk. Conclusions. Upregulation of HLA-DR antigen in the conjunctival epithelium of SS patients may be regulated by IFN-γ through the activation of NF-κB.