CYTOKINE MESSENGER-RNA EXPRESSION IN THE LABIAL SALIVARY-GLAND TISSUES FROM PATIENTS WITH PRIMARY SJOGRENS-SYNDROME

The pattern of cytokine mRNA expression in frozen minor salivary gland tissues from patients with primary Sjogren's syndrome (pSS) (n = 12) and controls (n = 8) using an in situ hybridization technique and oligonucleotide probes of interleukin-1 beta (IL-1 beta), tumour necrosis factor alpha and beta (TNF-alpha and TNF-beta), interleukin-6 (IL-6), interleukin-2 (IL-7) and its receptor (IL-2R), interleukin-4 (IL-4), interleukin-10 (IL-IO), interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) was examined. In addition to in situ hybridization, immunohistochemistry was used to identify the subset of cells expressing IL-2 and IL-4 mRNA. Mononuclear cells involved in the minor salivary gland lesions of pSS patients were found to express mRNA for pro-inflammatory cytokines such as TNF-alpha and IL-1 beta, and cytokines involved in the regulation of B- and T-cell function (IL-2 and IL-6). In contrast, only three biopsies from patients with pSS express mRNA of inhibitory cytokines such as IFN-gamma and TGF-beta. Furthermore mRNA for IL-6 and IL-1 beta was also detected in the glandular epithelial cells suggesting that these cells may play a role in the pathogenesis of autoimmune lesion in Sjogren's syndrome. IL-IO mRNA was not detected while IL-4 mRNA was primarily detected in naive T-lymphocytes of patients with a mild and early lesion. These results suggest that local production of cytokines by both mononuclear and epithelial cells may be involved in the immune-mediated destruction of exocrine glands in patients with pSS.