Expression of interferon-inducible T cell α chemoattractant (CXCL11) in the salivary glands of patients with Sjögrenʹs syndrome

To investigate the possible involvement of interferon-inducible T cell α chemoattractant (I-TAC or CXCL11) in the salivary gland lesions of Sjögrenʹs syndrome (SS), I-TAC mRNA expression was assayed in cultured salivary epithelial cells by reverse transcriptase-polymerase chain reaction (RT-PCR). This transcript was not expressed by SS salivary epithelial cells in the absence of IFNγ, but was expressed after cells were stimulated with IFNγ. We found that IFNγ was the only cytokine that induced I-TAC mRNA expression. I-TAC proteins were shown by ELISA to be secreted into the culture supernatants of SS salivary epithelial cells following IFNγ stimulation. Moreover, immunohistochemical assays of minor salivary glands (MSG) showed that I-TAC was predominantly located in the ductal epithelium adjacent to lymphoid infiltrates in the SS salivary gland, indicating that ductal epithelial cells produce I-TAC proteins in response to stimulation with IFNγ secreted by lymphocytes that infiltrate into SS salivary glands. In contrast, I-TAC proteins were virtually absent from normal salivary glands. These findings suggest that I-TAC is involved in the development of salivary gland lesions observed in SS.